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Tomorrow is my exam and I came across this question in my practice paper again. I hate this type of questions a lot. Can you help? The second question is:

Mrs Kumar paid $14 438 for 5 similar laptops and 4 similar DVD players. If 1 laptop and 1 DVD player cost $2960 altogether, what was the cost of each DVD player?

CalculatorPlease9987  May 11, 2017
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Mrs Kumar paid $14 438 for 5 similar laptops and 4 similar DVD players.

If 1 laptop and 1 DVD player cost $2960 altogether,

what was the cost of each DVD player?

 

Let x = laptop
Let y = DVD player

 

\(\begin{array}{|lrcll|} \hline (1) & x+y &=& $2960 \quad & | \quad -y \\ & x &=& 2960 - y \\\\ (2) & 5x+4y &=& $14438 \quad & | \quad x= 2960 - y \\ & 5\cdot (2960 - y) + 4y &=& 14438 \\ & 5\cdot 2960 - 5y + 4y &=& 14438 \\ & 14800 - 5y + 4y &=& 14438 \\ & 14800 - y &=& 14438 \quad & | \quad \cdot (-1) \\ & -14800 + y &=& -14438 \quad & | \quad +14800 \\ & y &=& 14800 - 14438 \\ & \mathbf{y} & \mathbf{=} & \mathbf{$362 } \\\\ & x &=& 2960 - y \quad & | \quad y= 362 \\ & x &=& 2960 - 362 \\ & \mathbf{x} & \mathbf{=} & \mathbf{$2598 } \\ \hline \end{array}\)

 

Each DVD player cost $362

 

laugh

heureka  May 11, 2017
edited by heureka  May 11, 2017
edited by heureka  May 11, 2017

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