"I never see what has been done; I only see what remains to be done."
- Marie Curie
4.
A number of friends decided to go on a picnic and planned to spend Rs. 96 on eatables. Four of them, however, did not turn up. As a consequence, the remaining ones had to contribute Rs. 4 each extra. The number of those who attended the picnic was
n=total no. of students.
r=rs. per student.
nr=96 i.e. r = 96/n
each students have to play 4rs. extra because 4 students did not turn up so:
(n-4)(r+4)=96
nr+4n-4r-16=96
n(96/n)+4n-4(96/n)-16=96
96+4n-4*96/n-16=96
4n*n-4*96-16n=0
n*n-4n-96=0
(n+8)(n-12)=0
n=12
n-4=8
