Answer:
b=-1
Explanation:
First you have 15= -11b +4
You want to subtract 4 from both sides, so on the left side you get 11 and on the right side you only have -11b because 4-4 cancels out and gets you 0.
11=-11b
Then divide both sides by -11 and the right side equals b and the left side equals -1. So, b = -1.