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.

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.

anonymous · Answer

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