a certain car increased its average speed by 4 miles per hour in each successive 5 - minute interval after the first interval . if in the first 5 - minute interval its average speed was 20 miles per hour , how many miles did the car travel in the third 5 - minute interval ?
"in the third time interval the average speed of the car was 20 + 4 + 5 = 29 miles per hour ; in 5 minutes ( 1 / 12 hour ) at that speed car would travel 29 * 1 / 12 = 2.5 miles . answer : d ."
multiply(add(add(20, 4), 5), divide(4, const_60))