Answer :

66 + 20 = 86
86 ÷ 2 = 43
43 inches

Algebraically is represented as 66 = 2x - 20
The 66 represents Carol's Height
Mindy's Height is represented by x
So 2 of Mindy's heights minus 20 inches is Carol's Height

66 = 2x - 20
86 = 2x             (Add 20 to both sides)
43 = x               (Divide both sides by 2)
66+20=86
86 divided by 2= 43
Mindy is 43 inches tall