simplify

There is no equal sign, so y can be any number.

8(2y-9)-(y+3)
Take the 8 and multiply 2y and 9 by it.
16y-72-(y+3)
Then make the ones left in parentheses negative. This is because of the - that occurs before the parentheses.
16y-72-y-3
Then simplify.
15y-75