Question

Lisa is choosing between two exercise routines. In Routine #1, she does only running, burning 8.5 calories per minute. In Routine #2, she burns 28 calories walking. She then runs at a rate that burns 2.9 calories per minute. For what amounts of time spent running will Routine #1 burn at least as many calories as Routine #2? Use t for the number of minutes spent running, and solve your inequaliy for t

Answer 1

Let, the number of minutes in running = t

Inequality would be: 8.5t ≥ 28 + 2.9t
Subtract 2.9t from both sides, 

8.5t - 2.9t ≥ 28 + 2.9t - 2.9t
5.6t ≥ 28

Now, divide by 5.6
5.6t/5.6 ≥ 28/5.6
t ≥ 5

In short, Your Answer would be at-least 5 minutes

Hope this helps!