Solve the equation

1/4 mile = 0.25 mile

6/5 mile = 1.2 mile

we need to go 1.2 miles. If we divide 1.2 by 0.25 we get 4 as the quotient and 0.2 as the remainder. that is

1.2/0.25 = 4(0.25) + 0.2

there are 4 complete groups of 0.25 miles . The first 0.25 mile will cost $2.5 and all the remaining ones will cost $0.4. The remaining 0.2 miles should be charged as if it was for 0.25 miles

Cost = 2.5 + 3*0.4 + 1*0.4

Cost = 2.5 + 1.2 + 0.4 = $4.1