Answer:
AB = 38
Explanation:
|<----------------- AB ------------------->|
A--------------------M--------------------B
5x + 4 3+16
since M is at midpoint, AM = MB
5x + 4 = 3 + 16
5x = 3 + 16 - 4
x = 15 / 5
x = 3
AB = AM + MB
AB = 5(3) + 4 + 3 + 16
AB = 15 + 23
AB = 38