Does a b average and a c average combined still make a b average? (b average is a 3.0 and a c average is a 2.0)

When amy exercises in her fitness center for 1 hr she burns a total of 475 calories.if she burns 9 calories a minute jogging on the treadmill and then burns 6.5 calories a minute pedaling on the stationary bicycle how many minutes of the hour does she spend exercising on the bicycle?