Dexter wrote:

=B1*IF(A1<36,0.7,IF(A1<=48,0.8,0.9))
Thank you! I understand what you are doing now. Only one question though.
Shouldn't it be A1= 48? Rather than <= 48?

No :)

if(expr, TRUE, FALSE)..

if A1<=48 same as NOT (A148)
then it's B1 * 0.8 (for the 20%)
else
then it's B1 * 0.9 (for the 10%)

Just another way of doing the math.