Hi,

This should work..
Stricke price in cell B1 (Format as number)
Discount in B2 (Format as pct)
Salestax in B3 (Format as pct)
Downpayment in B4 (Format as pct)
Amount to be financed in B5 (Formate as number)

=((B1-(B1*B2))+((B1-(B1*B2))*B3))-(((B1-(B1*B2))+((B1-(B1*B2))*B3))*B4)


Regards
Bondi