Jack has $800,000 in his pocket nothing but cash, but he spent 700,000 on parts for his plane. Jack is planning a road trip back home. if ga

Thanks Chris

I had to think quite hard about this - maybe I shouldn't admit that   :))

He has a maximum of   $100,000 for fuel

Fuel costs $400 per gallon so he has enough money for

100,000 / 400 = 250 gallons

Now the distance is 600 miles so it will be alright so long has he gets at least 

$$\frac{600\;miles}{250\;gallons}=\frac{2400\;miles}{1000\;gallons}=2.4miles/gallon$$

Just like Chris said   

As long as this inequality is satisfied, he can make it back home.....

($400)( 600) / x  ≤   $100,000    where x is the mpg of gas that his car gets ......so.....rearranging

240,000/100,000  ≤   x

2.4   ≤    x    

In other words, as long as his car gets at least 2.4 mpg of gas, he can make it back