Answer:
EF = 7
Explanation:
You want to know the length of midsegment EF in the triangle with it labeled 43-4x and the parallel base segment labeled 32-2x.
Midsegment
The midsegment is half the length of the base segment, so we have ...
(43 -4x) = 1/2(32 -2x)
43 -4x = 16 -x . . . . . simplify
27 = 3x . . . . . . . . add 4x-16
9 = x . . . . . . . . divide by 3
EF = 43 -4x = 43 -4(9) = 43 -36
EF = 7