Identify the missing base of the trapezoid, given that A=36 cm∧2. HELP PLEASE!!

Answer:
6 cm
Step-by-step explanation:
A = 1/2(b + 12)(4)
36 = 1/2(b + 12)(4)
72 = (b + 12)(4)
18 = b + 12
18 - 12 = b
6 = b
or
b = 6 cm