The Zj value for the quantity column provides the total contribution of the given solution
Zj (gross profit) = (Profit per unit of S1) (Number of units of S1) + (profit per unit of S2) (Number of units of S2)
= $0100units+$0240units = $0 profit
The Zj values in the other columns represent the
gross profit
variable into the current solution
given up by adding one unit of this
Zj = (Profit per unit of S1) (Substitution rate in row 1) + (profit per unit of S2) (Substitution rate in row 2)