Describe specific ways your friend can use frequency, intensity, time, and type to safely apply the overload principles to his workout schedule. provide two ways per training principle.

sunday 30-minute bike ride
monday 20 push-ups, 10 squats, and 20-minute jog
tuesday 30-minute bike ride
wednesday rest
thursday 20 push-ups, 10 squats, 25 curl-ups, and 20-minute jog
friday 30-minute bike ride
saturday one-hour walk

Sunday -- start the week off strong, instead of 30 mins push for 45 to get that extra push or instead of 30 mins cut it to 15-20 mins of high intensity
Monday -- keep all of the workouts although add weights to build muscle faster
Tuesday -- make it 40 mins instead or keep it at 30 and go uphill
Wednesday -- resting is good, give your muscles time to recover 
Thursday -- 20 min jog is perfect for a warm up, push your limits and double each workout, 20 push-ups? no. 40.   10 squats? no. 20.   25 curl-ups? no. 50. 
Friday -- 30 min bike ride is good. Sprint as fast as you can to finish the week strong
Saturday -- one-hour walk is good though you should do this more frequently

To every exercise add weights. 

Sunday: instead of a 30-minute bike ride, reduce it to 20 minutes
Monday: 20 push-ups, 10 squats, and 10-minute jog
Tuesday: Instead of a 30-minute bike ride, reduce it to 10 minutes
Wednesday: Rest
Thursday: 20 push-ups, 10 squats, 25 curl-ups, and 10-minute jog
Friday: rest
Saturday: rest