To represent the situation with a system of equations, we can define:
- \( x \): the number of sandwiches ordered (each costing $5)
- \( y \): the number of combos ordered (each costing $8)
From the problem, we know two things:
-
The total number of meals ordered by Sonji and her 8 friends is 9, which gives us the equation: \[ x + y = 9 \]
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The total cost of the meals is $66, which gives us the equation based on the prices: \[ 5x + 8y = 66 \]
Thus, the correct system of equations that represents the number of meals of each type that Sonji and her friends purchased is: \[ \begin{align*} x + y & = 9 \ 5x + 8y & = 66 \end{align*} \]
So the correct choice is: \(x + y = 9\); \(5x + 8y = 66\).