If we assume they work at a constant rate of 2/15 of a mile in 20 minutes then we can assume they work the same amount each time in 1 hour as:
20 x 3 = 60 minutes~ 1 hour
Therefore we can multiply 2/15 by 3 to go our answer:
2/15 x 3/1 = 6/15
Therefore they will pave 6/15 of a mile in an hour
