Expenses can be represented as the sum of fixed and variable costs and variable costs are the product of unit costs times the number of units
Profit =Revenue – (Fixed cost + Variable cost)
Profit =(Selling price per unit)(number of units sold) – [Fixed cost + (Variable costs per unit)(Number of units sold)]
Profit =sX – [f + vX]
Profit =sX – f – vX
where
s = selling price per unit
 
v = variable cost per unit
f = fixed cost
 
X = number of units sold