Question

2b=6a-14 3a-b=7

Answer 1

I'm not sure what you are looking for here
2b=6a-14
3a-b=7

You could take the first equation of
2b=6a-14 and divide by 2
b=3a-7

or you could take the 2nd equation first, since the b is by itself
3a-b=7
3a-b+b=7+b
3a=7+b
3a-7=7-7+b
3a-7=b
b=3a-7

But either way, this is always true, they are the same equation