Question

Solve for b.
ab + c = d
b = a + c/d
b = a/(c - d)
b = (d - c)/a

Answer 1

=> ab^2 + cb = bd (multiplying both sides by b)
=>b(ab + c) = bd
=> ab + c = bd / b
=> ab + c = d (cancelling out b from numerator and denominator)

Answer 2

so the first one?

Answer 3

YEP!