At a certain photoprocessing shop, the first standard-size print of a negative costs $4, and each additional print of the same negative costs $1. What is the total cost, in dollars, of y standard-size prints of each of x different negatives?A. 4xy + (x - 1)y
B. 4xy + (y - 1)x
C. 4x + xy
D. 4x + xy - 1
E. 4x + x(y - 1)
The first print of a negative costs $4, and
each additional print of the same negative costs $1.
One print of a negative costs $4;
Two prints of the negative cost $4 (for the first print) plus $1 (for the second print) = $5
Three prints of the negative cost $4 (for the first print) plus $1 (for the second print) + $1 (for the third print) = $6
...
So, the first print costs $4 and all subsequent prints of the same negative cost $1 each.
Now, y prints of a negatives will cost $4 for the first print, and $1 for each of the the remaining prints of the negative, so $1 for each of the remaining (y-1) prints. So, the total of $4*1 + $1*(y - 1). For example:
10 prints of a negatives will cost $4 for the first print, and $1 for each of the the remaining 10 -1 = 9 prints of that negative: $4*1 + $1*(10 - 1).
Now, if we have x different negatives, then to print y prints of each, we'd need x*(4 + (y - 1)) = 4x + x(y - 1). For example:
Say we have 3 different negatives and want to print 10 prints of each. 10 prints of one negative will cost 4 + (10 - 1) dollars and 10 prints of 3 different negatives will cost 3*(4 + (10 - 1)).
Answer: E.