Question

Three brothers combine their money to buy their father a birthday gift. If each brother contributes fifteen dollars and one brother contributes an additional twenty-five dollars , how much money do they have for the gift? The expression is fifteen b plus twenty-five , where b represents the total number of brothers.

Answer 1

It tells you the expression is:
15b+25=$amount
and that the number of brothers (b) = 3...so just solve it using that info.