C i thinks, but im not even sure so
Step-by-step explanation:

Answer:
x = 13.5
BC = 30
Step-by-step explanation:
BC is double the length of DE. And we know that DE is equal to 15. So 15 x 2 is 30.
Now to find x. We know that our answer has to add up to 30. So we first subtract 3 from 30 to get 27. Then divide 27 by 2 to get what x is equal to. x = 13.5
V=pi•r^2•h. So, 3.14•16•10=502.4
Answer:
5-2(-4x+10)-5x----open brackets and multiply
5+8x-20-5x----combine like terms
8x-5x+5-20
3x-15
3(x-5)