Answer:
D
Step-by-step explanation:
Since B is the midpoint of AC , then
AB = BC , substitute values
4x + 3 = 3x + 9 ( subtract 3x from both sides )
x + 3 = 9 ( subtract 3 from both sides )
x = 6
Then
AC = AB + BC
= 4x + 3 + 3x + 9
= 7x + 12
= 7(6) + 12
= 42 + 12
= 54 → D
