9514 1404 393
Answer:
Step-by-step 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
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Additional comment
We put the coefficient of x as 0 in the last equation to facilitate writing this system as an augmented matrix.
[tex]\left[\begin{array}{ccc|c}1&1&1&500\\2.50&1.75&3.20&1172.50\\0&1&-1&100\end{array}\right][/tex]
The solution is (x, y, z) = (300, 150, 50).