Looking for some clarity.

I had the following test problem in "order of operations"

36/4(5-3)+6 and gave 9 as the answer. According to the rules I was wrong. the answer was 33

If I had the equation Y=36/4(a+b)+6 and rewrite as:

36

Y= ___________ +6

4(a+b)

And use a=5, b=-2 then Y=9

What am I missing?

mfoam