Answer:
BC = 39
Step-by-step explanation:
Given:
DC = 5x - 18,
BC = 3x - 6,
AB = 2x + 12
Opposite sides of a parallelogram are equal.
Therefore:
AB = DC
2x + 12 = 5x - 18
Collect like terms
12 + 18 = 5x - 3x
30 = 2x
Divide both sides by 2
15 = x
x = 15
BC = 3x - 6
Plug in the value of x
BC = 3(15) - 6 = 45 - 6
BC = 39