Answer:
Amanda's method is linear because the number of minutes increased by an equal number every week. Billy's method is linear because the number of minutes increased by an equal factor every week
Explanation:
Amount of exercise in minutes for Amanda : 10 , 20 , 30 , 40
Amount of exercise in minutes for Billy : 10 , 20 , 40 , 80
Amanda's amount of exercise increases 10 minutes each week
10 + 10 = 20 20 + 10 = 30 30 + 10 = 40
Billy's amount of exercise increases by factor 2 each week
10 x 2 = 20 20 x 2 = 40 40 x 2 = 80