Answer:
x = 4
Step-by-step explanation:
We know that M is the mid-point of AB. So,
AM = BM ( A mid point divides a line segment into 2 equal parts. )
Also it's given that length of AM is 20 & length of BM is 3x + 8.
But as AM = BM ,
[tex]20 = 3x + 8[/tex]
[tex] = > 3x = 20 - 8 = 12[/tex]
[tex] = > x = \frac{12}{3} = 4[/tex]