Answer:
BC = 11
Explanation:
Since A , B and C lie on a straight line , then
AB + BC = AC ( substitute values )
5x + 2 + 6x + 5 = 18 ( simplify left side )
11x + 7 = 18 ( subtract 7 from both sides )
11x = 11 ( divide both sides by 11 )
x = 1
Then
BC = 6x + 5 = 6(1) + 5 = 6 + 5 = 11