6+4 over 5b = 9 over 10bSolve
(6+4)/5b = 9/10b10/5b = 9/10b(Multiply both sides by 5b)10 = 5b * 9/10b10 = 45b/10b10 = 35b(Divide both sides by 35)10/35 = b2/7 = b