15x + 28y = 116
x + y = 6
that would be ur system of equations
5 rows of 10 photos and last row with 3 photos,
6 rows of 8 photos and last row with 5 photos,
7 rows of 7 photos and last row with 4 photos,
Also, reverse the rows and photos in each row (ex 5 rows 10 photos=10 rows 5 photos) to get another 3 sets.
18a-14 Would be your answer because you are basically distributing which is taking the number on the out side of the parenthesis and multiplying it by all the numbers inside of the parenthesis