Answer:
x = 2
Explanation:
DF is a mid segment and is half the sum of the parallel bases, that is
2x + 5 =
( multiply both sides by 2 to clear the fraction )
4x + 10 = 8 + 5x ( subtract 4x from both sides )
10 = 8 + x ( subtract 8 from both sides )
2 = x