Question

Mr. Smith goes to the concession stand and buys 2 soft pretzels and 1 cheeseburger for $8.25. Mr. Martin goes to the same concession stand and buys 1 soft pretzel and 3 cheeseburgers for $13.50. Write a system of equations and solve to determine the cost of a cheesburger.

Answer 1

$4.15

Explanation:

Let the cost of a cheeseburger be x

Let the cost of a soft pretzels be y

If Mr. Smith goes to the concession stand and buys 2 soft pretzels and 1 cheeseburger for $8.25, this is expressed as;

x + 2y = 8.25 .... 1

Also, if Mr. Martin goes to the same concession stand and buys 1 soft pretzel and 3 cheeseburgers for $13.50, this is expressed as;

3x + y = 13. 50..... 2

The required equations are:

x + 2y = 8.25

3x + y = 13. 50

Find x and y by solving simultaneously:

From 1: x + 2y = 8.25

x = 8.25 - 2y ..... 3

Substitute 3 into 2

3(8.25-2y)+y = 13.50

24.75 - 6y+y = 13.50

24.75 - 5y = 13.50

-5y = 14.50 - 24.75

-5 y = 10.25

y = -10.25/-5

y = 2.05

Since x = 8.25 - 2y

x = 8.25 - 2(2.05)

x = 8.25 - 4.1

x = 4.15

Hence the cost of a cheesburger is $4.15