I want to creat a easy-to-use formula to measure the intensity of a exercise workout.

The input factors are:
1. Minutes exercise.
2. Miles run.
3. Calories burned.
4. Level of treadmill.

So, if:

Minutes = 50
Miles = 4
Calories = 423
Level = 10

Therefore, what is the overall intensity of the workout using these four numbers?

Thank you for your help.

Stuart