Ok so we let's assume the amount of whole miles David can drive on a $250 budget is "x" miles. This means that if he uses it for 3 days,
[tex]80.85 + 0.26x \leqslant 250[/tex]
because he isn't allowed to exceed that limit.
So:
[tex]0.26x = 169.15[/tex]
And:
[tex]x = 650.57[/tex]
However, David can only drive in whole miles, and doesn't have enough money to drive the extra 0.43 miles, hence we round down to 650.
So he can drive 650 miles without exceeding his limit.
Hope this helped
