"marina burns calories at a rate of 15 calories per minute when running and 6 calories per minute when walking. suppose she exercises for 60 minutes by running for r minutes and walking for the remaining time. the expression 15r+6(60-r) represents the calories burned. what does each term represent? "

Step-by-step explanation:

Marina burns calories at a rate of 15 calories per minute when running.

Let she runs for r minutes.

Therefore, number of calories burnt in r minutes running = 15r calories

Now it is given that she exercises for 60 minutes, in which she runs for r minutes so remaining time for walking will be = (60 - r) minutes

Calories burnt in walking is given as 6 calories per minute

Therefore, calories burnt in (60 - r) minutes walking= 6(60 - r) calories.

Finally total calories burnt in exercising for 60 minutes will be represented by [60r + 6(60 - r)] calories.