y=mx+b

1. y=2x+4

2. what you would do is subtract 4 from both sides then the two fours that you have will cancel each other out then you would end up with

3. 2x -4 = -2=x

4. then you would reenter that in order to get b so what you would do is

5. -2=x+4

6. then once you've written that down you would subtract -2 from both sides which would leave you with

7. 4- -2= 6=b

8. so your b is 6

9. then that is your answer to the problem.