If the average of 12, 7, 9, a, and b is 12, then
what is the average of a + b?
we know that
the average is equal to
(12+7+9+a+b)/5=12
simplify
(28+a+b)/5=12
Multiply both sides by 5
28+a+b=60
isolate (a+b)
a+b=60-28
a+b=32
average a+b
a+b/2=32/2=16
answer is 16