A car is travelling 1.75 miles in 2-1/3 minutes.How far in 21 minutes? To find the answer, find out what number you have to multiply 2-1/3 by to get 21. Then multiply that same number by 1.75 and you find your answer.
If you divide 21 by 2-1/3 you get 9 , so the car will travel 9 miles in 21 minutes. In one hour, (60 minutes) you set up an equation: 9/21=x/60. Cross multiply 60*9 and divide by 21.=540/21=25.7 miles.