(1st * 25) + (2nd * 30) = 1250
1st + 2nd = 45
solve the system for 1st and 2nd
A family has two cars. The first car has a fuel efficiency of 25 miles per gallon of gas and the second has a fuel efficiency of 30 miles per gallon of gas. During one particular week, the two cars went a combined total of 1250 miles, for a total gas consumption of 45 gallons. How many gallons were consumed by each of the two cars that week?
2 answers
1st car used X gal.
2nd car used Y gal.
Eq1: x + y = 45
Eq2: 25x + 30y = 1250
Multiply Eq1 by -25 and add the Eqs.:
-25x - 25y = -1125
25x + 30y = 1250
sum: 5y = 125
Y = 25
In Eq1, replace Y with 25 and solve for X.
2nd car used Y gal.
Eq1: x + y = 45
Eq2: 25x + 30y = 1250
Multiply Eq1 by -25 and add the Eqs.:
-25x - 25y = -1125
25x + 30y = 1250
sum: 5y = 125
Y = 25
In Eq1, replace Y with 25 and solve for X.
4 answers