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40 votes
40 votes
Kenneth bought 15 chicken sandwiches and tuna sandwiches for $35.10. Each chicken sandwich costs $2.30 and each tuna sandwich costs $2.40. How many chicken sandwiches did Kenneth buy?

Help! Can you do a guess and check? Awarding 20 points!

NONSENSE=REPORT​

User MatthewFord
by
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1 Answer

11 votes
11 votes

Answer:

the number of chicken sandwiches = 9

Explanation:

let x be the number of chicken sandwiches

y be the number of tuna sandwiches

We have to solve this system:


\begin{cases}x+y=15&\\ 2.3x+2.4y=35.1&\end{cases}


\Longleftrightarrow \begin{cases}y=15-x&\\ 2.3x+ 2.4(15-x)=35.1&\end{cases}


\Longleftrightarrow \begin{cases}y=15-x&\\ 2.3x+ 36 -2.4x=35.1&\end{cases}


\Longleftrightarrow \begin{cases}y=15-x&\\ -0.1x + 36=35.1&\end{cases}


\Longleftrightarrow \begin{cases}y=15-x&\\ -0.1x=-0.9&\end{cases}


\Longleftrightarrow \begin{cases}y=15-x&\\ x = 9&\end{cases}


\Longleftrightarrow \begin{cases}y=15-9=6&\\ x = 9&\end{cases}

User Jontatas
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