Answer:
x = 3
Step-by-step explanation:
We should know that:
A straight segment joining the middle of two sides in a triangle is parallel to the third side and equal to half of it.
So,
3x + 1 = (1/2) * 20 = 10
3x = 10 - 1 = 9
x = 9/3 = 3
So, the value of x = 3
