Question 28292
In city her speed = 15mi/gal
On highway her speed = 25mi/gal
Total miles driven = 220 by both the city speed and the highway speed.
Total gallons of gas used (with city and highway speeds) = 11


Since 11 in the highest gallons used you know that the "x" value of which gallons of gas you are trying the find will be less than 11.


We want to find the gallons of gas for city first.
SO Mi driven in city = 17x
With mi driven on highway = 25(11-x)
Total miles driven = 220


Equation:
17x+25(11-x)=220
17x-25x=220-275
-8x=-55
x=6.875 (gallons used for city)


11-6.875=4.125 (gallon used on highway)


6.875(17)=116.875 (miles driven in city)
25(4.125)=103.125 (miles driven on highway)


Hence, she drove 116.875 miles in city and 103.125 miles on the highway.


Paul.