N is the number of buttons in a sewing box.

N is more than 40 but less than 80.
When N is divided by 5 , the remainder is 2.
When N is divided by 7, the remainder is 4. What is the value of N?

1 answer

Given some integers a and b,

N=5a+2
N=7b+4

Candidates for N using a and b are thus
a: 42,47,52,57,62,67,72,77
b: 44,51,58,65,72,79

Looks like we have a winner at N=72