Here they have told you the extended amount of time and what that would give you. 8 kilometers=60 minutes, yes?
This is a ratio, meaning that you can have mulitiple numbers that mean the same thing.
You would, instead of multiplying like you would for a number larger than you're looking for, would simply divide both sides by the same number so that they'll stay even and balanced, the values unchanged.
So 8 and 60 have a same multiple, 4.
Divide four on both sides to get 2 and 15.
2 would be the number of kilometers you are looking for and 15 would be the number of minutes that Tonya would need to run.
