She will be able to travel 36 blocks in the 12 minutes at that rate.
So, the size of the smaller squares will be 6 by 6. So the radius should be 3.
Ok...don't have the statements, but the equations would be:
y=20+10X
y=50+5X
They would be equal in cost at X=6... For more than 6 days, the gym would be cheaper. For less than 6, the classes would be cheaper.
Just times it all together, the same rules apply for finding the area.