Answer:
Well, this is not an answer but, i would like do know your grade. ( & WHO'S idea was it to add LETTERS to MATH!?)
3 (x-7) = 9
X-7 = 3
X = 10
B is the answer
Answer:
6x-21
Step-by-step explanation:
1) draw diagram (in image)
BD=2x-21+4x
combine Like terms
6x-21
Problem 1 should be B, C, and D. I'm not sure about the rest... Sorry I couldn't be more of a help.