Question

The boy gets 3 marks for each correct sum and losses 2 marks for each incorrect some he does 24 sums and obtain 37 marks the number of correct sums were

Answer 1

let x be the correct sum out of 24

so 24-x is incorrect sum

according to condition ,

each incorrect sum looses 3 marks of that sum plus additional 2 marks for wrong sum

so

3x - 2( 24-x) = 37

3x - 48 + 2x = 37

5x = 37 + 48

5x = 85

x = 17

so correct sums are 17