Answer:
D
Step-by-step explanation:
Since the constructed line is a perpendicular bisector of the line AB, then
AC = BC ← substitute values
4x + 12 = 2x + 18 ( subtract 2x from both sides )
2x + 12 = 18 ( subtract 12 from both sides )
2x = 6 ( divide both sides by 2 )
x = 3
Hence
AB = 2AC = 2(4x + 12) ← substitute x = 3
AB = 2(12 + 12) = 2 × 24 = 48 → D
