Question

A boy gets 3 marks for each correct sumand losses 2 marks for each incorrect sum He does24 sums and obtain 37 Mark the number of correct sums were

Answer 1

Let the no. of correct sum be x and incorrect sum be y
Given,total sum=24
Therefore,x+y=24
=>x=24-y -(1)
Also,3x-2y=37 -(2)
=>3(24-y)-2y=37
=>72-3y-2y=37
=>-5y=37-72
=>y=9
from (1),we get,
x=24-9
=15
Thus,the no. of correct sums were 15