Equation for company A is A=121 where A is dollars.
Equation for company B is B=65+0.70m where m is the mileage.
A<B when 121<65+0.70m,
56<0.70m,
56/0.70<m, m>56/0.70=560/7=80 miles.
So the mileage needs to be more than 80 for A to charge less than B.