Work shown above! Answer to both is A
12(3-2x) = 84
do distributive multiplication:
12(3) + 12(-2x) = 84
36 - 24x = 84
Deduct 36 to both sides
36 - 36 - 24x = 84 - 36
-24x = 48
divide -24 to both sides
-24x / -24 = 48/-24
x = -2
To check:
12(3-2x) = 84
12(3-2(-2) = 84
12(3+4) = 84
12(7) = 84
84 = 84
I’m pretty sure your answers are right
(B) Opposite sides are equal (otherwise, trapezoid, etc)