Question

2b+4+5b+7= -10

Answer 1

Hi first add like-terms together like this 6b-8b=-2b

Answer 2

Then keep the variable alona in one side like this :
10b + 6 = 5 becomes 10b = 5 - 6

Answer 3

Then divide by the number next to your variable like this :
7b = -21 becomes b = -21/7 = -3