Question

3(x+2y)=7y-9 when y=3

Answer 1

I'll do it step by step:

3(x+2(3))=7(3)-9
3(x+6)=21-9
3x+18=12

I don't know what x is, so I think that's as much as I can do. 

Answer 2

First substitute all of the y's with the value of y, like so:
3{x+(2*3)} = 7*3-9
Solve for x.
3{x+(6)} = 21-9
3(x+6)=12
x+6=4
x=(-2)
Hope this helps, please mark brainliest, I am one away from my next rank, and have an amazing day.