How to nest two IF statements

Hope this is clearer:

Condition Result if true Else
B24=1 and C24= 10 D24= 10 -5 (i.e., for any B24 <> 1 -- e.g., B24=0)
B24=1 and C24= -10 D24= -10 "" (i.e., for any B24 <> 1 -- e.g., B24=0)