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!