Able Transport operates a tour bus that they lease with terms that involve a fixed fee each month plus a charge for each mile driven. Able Transport drove the tour bus $4,000$ miles and paid a total of $$1,250$ in March. In April, they paid $$970$ for $3,000$ miles.

A$.$ What is the variable cost per mile if Able Transport uses the high$-$low method to analyze costs?

B$.$ What is the total fixed fee if Able Transport uses the high$-$low method to analyze costs?

C$.$ Using the answers from A and $B,$ complete the equation: Total cost$=$