First, create equations. Let x equal the miles driven. The first plan expression is 38 + 0.12x and the second plan expression is 51 + 0.08x. Setting these equal and solve for x: 38 + 0.12x = 51 + 0.08x -> 0.04x = 13 -> x = 325 miles.
The cost is found by substituting it into any of the expressions: 51 + 0.08(325) = 77 or 38 + 0.12(325) = 77
