Costs associated with two alternatives, code$-$named Q and R$,$ being considered by Albiston Corporation are listed below:

Alternative Q Alternative R

Supplies costs $ $85,000$ $ $85,000$

Power costs $ $38,000$ $ $37,200$

Inspection costs $ $35,000$ $ $37,200$

Assembly costs $ $46,000$ $ $46,000$

Required:

Which costs are relevant and which are not relevant in the choice between these two alternatives?

What is the differential cost between the two alternatives?