Answer:
x = 2
Step-by-step explanation:
EF = ½(BC + AD) => Trapezoid Midsegment theorem
Substitute
5x + 4 = ½((4x + 1) + (7x + 5))
5x + 4 = ½(4x + 1 + 7x + 5)
Multiply both side by 2
2(5x + 4) = 4x + 1 + 7x + 5
10x + 8 = 4x + 1 + 7x + 5
10x + 8 = 11x + 6
Collect like terms
10x - 11x = -8 + 6
-x = -2
Divide both sides by -1
x = 2
