Answer:
-7x - 18
Step-by-step explanation:
-4x - 10 - 3x - 8 = - 7x - 18
BC = BD + DC
8x = 4x + 10 + 3x +8
8x = 4x + 3x + 10 +8
8x = 7x + 18
8x - 7x = 18
x = 18
BC = 8x = 8*18 = 144 units