Fred drives an average of $15,000$ miles per year, and his car gets $20$ miles per gallon of gasoline.
- The average cost of gasoline is $\$3.25 $ per gallon.
- He buys a new car. In his new car Fred continues to average $15,000$ miles per year, and the average cost of gasoline remains the same.
Approximately how many more miles per gallon does the new car get of Fred has a savings of $\$650$ per year on gasoline?
So for this this is what I've got: $15000/20=750$ to find the gallons drove and than multiply that by $3.25$ so I would get $750\cdot 3.25=2437.5$ and I subtract that by $650$ because $650$ is saved.
Now I have stuck. after this what do i do?
And sorry for not editing this correctly, I'm using my phone.
Let $M$ be the number of miles driven, $m$ be the mileage in miles per gallon, and $P$ be the price per gallon in dollars.
Then,
$$\left[\frac{M_{old}}{m_{old}} - \frac{M_{new}}{m_{new}}\right]P = 650.$$
The only unknown here is $m_{new}$ so you can solve for it.