Question

It costs $1.80 less to travel 100 miles in one car than it did to travel 80 miles in another. The average cost per mile of the former is 6 cents less than the average cost per mile of the latter. Find the cost per mile of each.

Answer 1

Let x be average cost per mile in 1st car and y in the second
\[100x +1.80= 80y\]
\[x+0.06 = y\]
Solving
\[100x+1.80 = 80(x+0.06)=80x+4.8\]
\[20x=3\]
\[x=0.15\]
\[y=0.21\]