# Aptitude - Problems on Ages - Discussion

### Discussion :: Problems on Ages - General Questions (Q.No.11)

11.

The present ages of three persons in proportions 4 : 7 : 9. Eight years ago, the sum of their ages was 56. Find their present ages (in years).

 [A]. 8, 20, 28 [B]. 16, 28, 36 [C]. 20, 35, 45 [D]. None of these

Explanation:

Let their present ages be 4x, 7x and 9x years respectively.

Then, (4x - 8) + (7x - 8) + (9x - 8) = 56 20x = 80 x = 4. Their present ages are 4x = 16 years, 7x = 28 years and 9x = 36 years respectively.

 Neha said: (Jul 3, 2010) How 20x comes?

 Faruk said: (Aug 23, 2010) 4x+7x+9x = 56+8+8+8 20x = 80 is it simplified.

 Affrin said: (Dec 16, 2010) (4x-8)+(7x-8)+(9x-8) = 56 --->(1) Now add all the "x" values and "numerical number" separetely in eqn (1) then we get: 4x+7x+9x = 20x (-8)+(-8)+(-8) = -24 20x-24 = 56 20x = 56+24 20x = 80 x = 80/20 x = 4 so,for calculating the current age we are substituting x=4 in (4x:7x:9x)= we get the ratio as 16:28:36

 Habib said: (Feb 20, 2011) For such ques......jst simply look at the options !!!! Try subtracting 8 frm B...and den add u get 56 !!!! Hit and Trial...saves time !!!! :)

 Jagadeesh said: (Mar 4, 2011) 4x+7x+9x=80 20x=80 x=4 then we get answer

 Rahima said: (Mar 23, 2011) Just add all the x terms and numerical terms seperately.

 Shiva said: (Mar 24, 2011) Shiva (4x-8)+(7x-8)+(9x-8)= 56 Remove the braces. 4x-8+7x-8+9x-8 =56 Now seperate variables and numeric terms. 4x+7x+9x=56+8+8+8 20x=80 x=4. njoy.

 Payal said: (May 21, 2011) Habib method was good

 Ganesh said: (Jul 15, 2011) Nice and easy method.

 Pragathi said: (Aug 8, 2011) Actually ago means past time so we have to add it's my doubt some times you will add some times you subtract please clarify it.

 Sumit said: (Aug 19, 2011) @Habib method is good.

 Swetha said: (Sep 1, 2011) Habib method is good:-).

 Chenchu said: (Sep 12, 2011) Can't understand habib's method of subracting 8 from b.

 Ankit Rathore said: (Sep 18, 2011) Good explanation

 Vissu said: (Sep 27, 2011) Sum of there ages is 56 before 8 years then after 8 years it must be 64.

 Virendra Rajput said: (Nov 22, 2011) Just look option which are having given ratio 4:7:9 A and D are ruled out then check 2"nd condition.

 Madhu said: (Nov 30, 2011) Ago means we can subtract that given value, after means add that value.

 Adinarayana said: (Dec 5, 2011) Faruk explained detail but I didn't understand, how is it came 8, how did you take the 56+8+8+8.

 Ronak said: (Dec 28, 2012) The total of ratios is 20 (4+7+9). The total of ages will become 56 + (8x3) = 56+24 = 80. Now 20 x 4 = 80, So the multiple is 4. So the common multiple is 4 for all. Now we get present ages of all. 4x4 = 16. 7x4 = 28. 9x4 = 36.

 Anu said: (Jan 6, 2013) When should we use (+) and (-) symbols under this section means problems based on age.

 Vijay Anand said: (Aug 23, 2013) @Anu. AGO means(-). SINCE, AFTER means(+).

 Sam said: (Jun 3, 2014) Search for the common multiplier. Here 4 matches exactly i.e., 4*4 = 16. 4*7 = 28. 4*9 = 36.

 Naveen Kumar said: (Jul 21, 2014) x(4+7+9) = 56+8+8+8. Then we got x = 4. For further answer each x term multiplied by 4.

 Vinutha said: (Aug 19, 2014) Simple method: 4*4 = 16. 7*4 = 28. 9*4 = 36.

 Djdave said: (Jan 4, 2015) f1:f2:f3 = 4:7:9. f1 + f2 + f3 - 24 = 56. f1 + f2 + f3 = 80. f1 = 4 / 20 * 80 = 16. f2 = 7/20 * 80 = 28. f3 = 9/20 * 80 = 36.

 Roshni said: (Jan 17, 2015) It is a ratio of three values then why plus is coming?

 Sanju said: (Aug 17, 2015) 4x-8+7x-8+9x-8=56 x=4 then 4x=16 is present ages.

 Ravi said: (Sep 25, 2015) Why they minuses with 8?

 Yunus said: (Nov 28, 2015) It is simple that eight years ago 56 and now 3 persons*8 years each = 24 years. So 56+24 = 80 now we check options the sum of 80 is 16+28+36 = 80 is option B answer.

 Karthika.L said: (Mar 1, 2016) Please explain in easy way?

 Ramya said: (Sep 28, 2016) It is simple method. He has given present ages of persons mentioned that 8 years ago, then we can take as; (4x - 8) + (7x - 8) + (9x - 8) = 56.

 Lavanya said: (Mar 2, 2017) 8 years ago sum of their age is 56, Present sum of their age is 80 Total parts of the ratio is 4+7+9 = 20 So, 80/20=4 4 * 4 ,7 * 4, 9 * 4 = 16, 28, 36.

 Pawan Kumar said: (Aug 4, 2017) How to add 8?

 Jon said: (Aug 7, 2017) I didn't understand. First of all, from where 80 came. Secondly, how do we know that we must plus, 4x-8 and 7x-8 how come there is + in between. Isn't it 8 years ago. Then why plus? Please, someone, explain in very simple manner.

 Tanweer said: (Sep 4, 2018) 8 year ago total age 56. Now 8x3=24+56=80 answer is B.

 Tirth Patel said: (Sep 23, 2018) 4 + 7 + 9 = 20x. Eight years ago* three persons(8*3)=24. Sum of their ages was= 56. 24+56=80x. 80/20=4. Then 4:7:9 multiply by 4. (4*4)=16, (7*4)=28, (9*4)=36. The Answer is 16, 28, 36.

 Krishan said: (Aug 18, 2019) 8 years ago the sum of ages was 56. At present, the sum of age will be 3*8+56 = 80.

 Swathi Hj said: (Oct 5, 2019) Can any one explain how that -8 comes.