Step-by-step explanation:
June: 18 miles in 90 minutes. Now you want to use the unit m/h; so we're going to find how many miles are rode in 1 hour. 1 hour is 60 minutes and 90 divided by 60 is 1.5. So you are also going to divide 18 by 1.5 which equals 12 m/h.
Chris: do the same equation for Chris; 72÷60= 1.2 and then 12÷1.2= 10 m/h.
