I will try to solve the problem in 2 ways. I'm not sure how the problem is supposed to read

8/(b+10) = 4/(2b-7) or (8/b) +10 = (4/2b) -7

whichever way is correct you need to get your b on one side of the equation

8/(b+10) = 4/(2b-7) or (8/b) +10 = (4/2b) -7

whichever way is correct you need to get your b on one side of the equation