Hello, begold91!

Max runs the first 4km of her training session at 8 km/h.

At least how many kilometers must she run at 15 km/h

in order to average 12 km/h for the whole session?

Max ran 4 km at 8 km/hr.

. . This took hours.

She will run more km at 15 km/hr.

. . This will take hours.

She will run a total of: hours.

She will run a total of km at an average speed of 12 km/hr.

. . Her total time will be: hours.

There is our equation! .