I suggest getting common denominator from this. I made everything into a 12,
3/12y - 8/12 = 10/12.
I added 8/12 to both sides;
3/12y = 18/12; multiplied both sides by 12,
3y = 18, then divided by 3 on both sides.
y = 6. There is the answer.
You can check by plugging y in, 1/4(6) - 2/3 = 5/6, make everything same denominator again, 3/12(6) - 8/12 = 10/12. Then multiply, 18/12 - 8/12 = 10/12, 10/12 = 10/12, meaning it is correct.