Answer:
Step-by-step explanation:
To find the unit rate we must divide the number of miles by the number of hours.
4miles / (2/9)miles = ( is given "He can cover 4 miles")
4 * (9/2)= ( dividing a number by a fraction is the same as multiplying the number by the inverse of the fraction; the inverse of 2/9 is 9/2)
36/2= ( because 4*(9/2) = 4*9/2 = 36/2)
18
The constant of proportionality is 18 miles per hour.
