so you want to isolate y. we do that by subtracting 1/2 from both sides. but since the denominators are not the same, we need to find a common denominator. In this case I would multiply 1/2 by 5 to get 5/10. so you subtract 7/10 by 5/10 and you get 2/10. We still want to simplify to 2/10=1/5
