If I have C7 as the constant but E7 or H7 or J7(depending on the imput) needs
to be multiplied by it- how can I make the answer appear in D7?

Example: C7 is product weight of 47 lbs
E7 is a qty of price level 1
H7 is a qty of price level 2
J7 is aqty of price level 3
Only one price level is to be chosen on a row but the weight remains the same.
so I would like to have the weight calculated with any possible price level
qty entered.