Mary spends her Saturday mornings buying groceries, helping her children with homework, cooking, and working on her weekend assignment. She does not always do these tasks in the same order. In how many possible ways can she do her tasks?

its 0.1 miles per minute

54 km / hours

step-by-step explanation:

we need to convert seconds to hours

60 seconds = 1 minutes

60 minutes = 1hour

15 m         60 second   60 minutes

  * *         = 54000 meters/ hour

second     1 minute             1 hour

now we need to convert meters to km

1000 m = 1 km

54000 m       1 km

*   = 54 km / hours

hour               1000m