To solve for y we need to use the inverse operation of addition which is subtraction. Lets do it:-
y + 8 = 35
y = ?
35 - 8 = ?
35 - 8 = 27
y = 27
CHECK OUR WORK:-
y + 8 = 35
y = 27
27 + 8 = ?
27 + 8 = 35
We were RIGHT!!!!
So, y = 27.
Hope I helped ya!! xD