Find the mean of the integers 5,-7,12,-10,15

= 5+(-7)+12+(-10)+15
= 32-17
= 15

15/5 = 3

The mean is found by summing the numbers up and dividing that sum by how many terms were in the set originally

we count 5 numbers
the sum is 5-7+12-10+15=-2+2+15=15

the sum divided by the number of numbers is the mean
15/5=3

the mean is 3