This is essentially the same as finding the slope....Let x be the minutes and y be the miles
So we have the following (x, y) points [ we only need two ] ...(3,36) and ( 5 , 60 )
Slope = change in miles / change in minutes = ( 60 -36 ) / 5 - 3 ) = 24 / 2 = 12 (miles per minute) → D