78.75
The sum of 75 plus 5 is 80.
(5 x 15) + (6 x 15) = 11 x 15 = 165
I cannot take this question seriously! The sum is 75.
75/(-5-10) = 75/(-15) = -5
3.75=5% of 75.
3.75 is 75% of 5.
75
75 + 5 = 80
'Sum' is pretty much a synonym for add, and 5+5 or 5 plus 5 is 10.
75 percent subtract 80 = -5
120*.5*.75=45
3.75 is 75% of 5.