Cost and revenue behavior

The following financial data have been determined from analyzing the records of Joe$$s Ceramics $($a one$-$product firm$)$:

Contribution margin per unit $$25$

Variable cost per unit $$21$

Annual fixed cost $$90,000$

How does each of the following measures change when product volume goes up by one unit at Joe$$s Ceramics?

a$.$ Total revenue $

Answer

b$.$ Total cost $

Answer

c$.$ Income before tax $