A family has two cars. The first car has a fuel efficiency of
40
miles per gallon of gas and the second has a fuel efficiency of
15
miles per gallon of gas. During one particular week, the two cars went a combined total of
1900
miles, for a total gas consumption of
60
gallons. How many gallons were consumed by each of the two cars that week?
Firstcar:gallons

Secondcar:gallons

Question

A family has two cars. The first car has a fuel efficiency of 
40
 miles per gallon of gas and the second has a fuel efficiency of 
15
 miles per gallon of gas. During one particular week, the two cars went a combined total of 
1900
 miles, for a total gas consumption of 
60
 gallons. How many gallons were consumed by each of the two cars that week?
Firstcar:gallons
 
Secondcar:gallons

aveline · Answer

Can you write two equations to model the situation?

jdcap · Answer

$$40f+15s=1900 \hspace{0.5cm}Eq.1\ f+s=60 \hspace{1cm}Eq.2 \ \color{orange}{Eq.1-40\times Eq.2}\-25s=-500\Rightarrow \,\color{blue}{s=20}\f=60-20\Rightarrow \color{blue}{f=40}$$