Answer:
B. 88.8
Step-by-step explanation:
let x represent class y
(x+71.2)/2=80 multiply each side by 2
x+71.2=160 subtract 71.2 by both sides
x=88.8
or
trial an error
replace x with each of the numbers and see if it plugs in.
example:
(80.5+71.2)/2=80
151.7/2=80
75.85=80?
false. incorrect
another example:
(88.8+71.2)/2=80
160/2=80
80=80?
true. correct
