After 3.5 hours, pasha had traveled 217 miles . if she travels at a constant speed , how far will she traveled after 4 hours?

In order for the function to be linear, what must m be and why? m = 22 because the rate of change is 1. m = 20 because the rate of change is 3. m = 22 because the rate of change is -1. m = 20 because the rate of change is -3.