Answer:
Assuming that Seiki wants to be as close to 40 minutes are possible (to the nearest minute), She would want to spend 7 minutes on each of the 3 cardio machines
Step-by-step explanation:
With Seiki wanting to spend at least 40 minutes exercising and spending 20 minutes lifting weights, she needs to spend at least 20 more minutes on her cardio. If we are looking for a number that is divisible by 3, that would mean that she would spend 21 minutes exercising.
