Ef is a median of trapezoid abcd. what is the value of x?

Since the given figure is a trapezoid, here is how we are going to find for the value of x. Firstly, the sum of the bases of the trapezoid is always equal to twice of the median. So it would look like this. 2M = A + B.
Plug in the given values above.
2M = (3x+1) + (7x+1)
2(10) = 10x + 2
20 = 10x + 2
20 - 2 = 10x
18 = 10x < divide both sides by 10 and we get,
1.8 = x
Therefore, the value of x in the given trapezoid is 1.8. Hope this is the answer that you are looking for. 

Bis the answer! hope this