Thank you for the opportunity to help you with your question!
lets get the time have to work as X
8 mph/1hr burns 840 cal
so 8 mph/75 min burns=840/60 *75
4mph/90 min burns =240 cal
so the time have to walk to burn the same number of calories =98.44 min
Please let me know if you need any clarification. I'm always happy to answer your questions.
15 Million Students Helped!
Sign up to view the full answer