Answer:
A - x = 4
Step-by-step explanation:
According to The Midsegment Trapezoid Theorem the length of the midsegment is the sum of both bases divided by 2.
So to find the value of x:
x + 3 + 4x 7 = 15*2 add like terms
5x + 10 = 30 subtract 10 from both sides
5x = 20 divide both sides by 5
x = 4