please help! i’ll mark brainliest

Answer:
B. 136
Step-by-step explanation:
∆ABC is similar to ∆EDC, therefore the ratio of their corresponding side lengths would be the same.
Thus:
AC/EC = AB/ED
(144 - x)/x = 51/3
(144 - x)/x = 17/1
Cross multiply
(144 - x)*1 = 17*x
144 - x = 17x
144 - x + x = 17x + x
144 = 18x
Divide both sides by 18
144/18 = 18x/18
8 = x
x = 8
✔️AC = 144 - x
Plug in the value of x
AC = 144 - 8
AC = 136