Aptitude - Time and Distance - Discussion

Hi friends there is a confusing point that how 61-x comes?

Hey Friends,

If Answer for PARTLY travelled is 16. Ok.

Means 4 km/ hr for foot he walked 16km.

And 9 km/hr for bicycle did 45 km ok.

Than 5 km/hr=45 means 9 km hr.

Now 4km/hr=16 means 4 km/hr.

So how it becomes partly ? Partly means 4:30 hr am I right. ?

Given that total distance travelled=61km and total time=9hrs.

Let x be the distance by foot.

And 61-x be the distance by bicycle.

s=d/t t=d/s.

9=x/4+ (61-x) /9.

By solving we gt 16 km.

@Tiru it's simple.

9 = x/4 + (61-x)/9...(1)
now take L.C.M for 4 and 9 i.e 36
9=(9x+4(61-x))/36
cross multiply
9*36=9x+244-4x
324=5x+244
5x=324-244
5x=80
x=80/5
x=16km

Please tell me 9*36 how it comes?

Hi penna, the problem is so simple..let me explain

Given that

Distance travelled by farmer =61 km in 9 hours

let the farmer travelled x distance by foot @ 4 km/hr

Therefore he travelled 61-x distance by bicycle @ 9 km/hr

already we know formula to find time, time = distance /speed

Time taken by the farmer = time taken on foot + taken by bicycle
9 = x/4 + 61-x/9

solving we can get x value.

We assumed that x is the distance covered by foot.

So that is the answer.

Can anybody explain this problem please.