The first thing you need to do is combine like terms.
3y-y+2y-5 = 7-2y + 5 (Subtract y)
2y + 2y -5 = 7-2y + 5 (Add 2y)
4y - 5 = 7-2y + 5 (add 5 and 7)
4y - 5 = 12-2y (add 2y to both sides)
6y - 5 = 12 (add 5 to both sides)
6y = 14 (divide by 6 on both sides)
y = 2.833333 (Simplify)
y = 2.83