The first standard-size print of a negative costs $4
Since there are x different negatives, the total cost for the first print of each negative = 4x

Each additional print of the same negative costs $1
He want a total of y standard-size prints.
Since already accounted for the first print, there are y - 1 prints to be completed.
Each print costs 1 dollar, so the cost is (1)(y - 1)
Since there are x negatives all together, the total cost = (x)(1)(y - 1)

TOTAL cost = 4x + (x)(1)(y - 1) = 4x + x(y - 1)

Answer: E