"lestie" wrote:
if hours<= 40, then gross pay=rate*hours, otherwise gross
pay=rate*hours+0.5* rate*(hours-40)
cell b4 rate
cell c4 hours

A couple of several ways to do it:

=b4*c4 + max(0, 0.5*b4*(c4-40))
=b4*c4 + if(c4<=0, 0, 0.5*b4*(c4-40))

if(gross pay-dependents*38.46)0, then federal tax=20%*(gross
pay-dependents*38.46), otherwisw federal tax=0
cell f4 gross pay
cell d4 dependents
cell i4 fed tax

In I4, one of the following (among others):

=max(0, 20%*(f4 - d4*38.46))
=if(f4 - d4*38.46 <= 0, 0, 20%*(f4 - d4*38.46))