Question 169682
so we have 72d+.16m for rate 1 and 144d+.08m for rate 2. where d is days and m is mileage.  set is to rate 2<rate 1  to find when rate 2 is less than rate 1
:
144(7)+.08m < 72(7)+.16m  
:
1008+.08m < 504+.16m
:
-.08m < -504.......we need to divide by -.08 remembering that when you divide by a negative that the inequality reverses.
:
{{{highlight(m>6300)}}}miles