solving rational proportions

When solving rational proportions you are trying to solve for x. In this proportion x + 3/4=2/5 you have to cross multiply and distribute. when this is done you should get this 5(x + 3) = (4)(2) then 5x + 15 = 8 in order to get x by its self you have to get ride of the 15. so you have to do the opposite operation and subtract 15 from both sides of the equal side. That becomes 5x = -7 you divide by 5 on both sides in order to get x alone. & your final answer would be x= -7/5