Question

A local foundation organized a lunch party for all the kids in the community. They ordered a total of 500 burger meals. They ordered plain burgers at $1.75 each cheeseburgers at $2.50 each, and chicken burgers

at $3.20 each. They ordered mostly cheeseburgers, and 100 fewer chicken burgers than plain burgers. The total order came to $1.172.50.
Define the variables and write a system of equations to represent the
situation.

Answer 1

9514 1404 393

Answer:

• x + y + z = 500
• 2.50x +1.75y +3.20z = 1172.50
• 0x +y -z = 100

Explanation:

Let x, y, z represent the numbers of cheeseburgers, plain burgers, and chicken burgers ordered for the party.

We have three relations given. Each can be used to write an equation.

x + y + z = 500 . . . . . . . . . a total of 500 meals were ordered

2.50x +1.75y +3.20z = 1172.50 . . . . . the total cost

0x +y -z = 100 . . . . . . . . . . 100 fewer chicken were ordered than plain

_____

Additional comment

We put the coefficient of x as 0 in the last equation to facilitate writing this system as an augmented matrix.

`\left[\begin{array}ccc1&1&1&500\\2.50&1.75&3.20&1172.50\\0&1&-1&100\end{array}\right]`

The solution is (x, y, z) = (300, 150, 50).