At a little-known vacation spot, taxi fares are a bargain. A 72-mile taxi ride takes 81 minutes and costs $64.80. You want to find the cost of a 38-minute taxi ride. What unit price do you need?
you need to calculate the cost by minute
$64.80/81=$0.80 per minute
therefore
multiply 0.80 by 38 min to obtain the total cost
0.80*38=$30.40