Excel 'IF' 'AND' formula

Hi,
I'm trying to create a formula where if 1st cell has one result the 2nd cell performs 'x'
But if the the 1st cell has a different result the 2nd cell performs 'y'.
E.G.
B2 = <90 then C2 = B2-90
But if
B2 = 0 then C2 =0
I've tried various combinations of 'IF' & 'OR' But can't get the result I want.
TIA