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Tyace needs at least 40 hot dogs and 40 buns for a cookout.
Packages of hotdogs cost $3.50 and contains 10 hotdogs.
Packages of buns cost $2.50 and contains 8 buns.
The maximum amount of money Tyace can spend on hot dogs and buns is $70.
What are possible combinations of packages that Tyace can buy?

 

I assume:


\(\text{Let packages of hotdogs $=x$ and $x_{min} = 4$ packages } \\ \text{Let packages of buns $=y$ and $y_{min} = 5$ packages }\)

 

\(\begin{array}{|rcll|} \hline \mathbf{\dfrac{$3.50}{10~hotdogs} * 10x + \dfrac{$2.50}{8~buns} * 8y} &=& \mathbf{$70} \\\\ \dfrac{$3.50}{ hotdogs} * x + \dfrac{$2.50}{ buns} * y &=& $ 70 \\\\ 3.50x + 2.50y &=& 70 \quad | \quad * 2 \\\\ \mathbf{7x + 5y} &=& \mathbf{140} \\ \hline \end{array}\)

 

Euler :

\(\begin{array}{|rclrclrcl|} \hline \mathbf{7x + 5y} &=& \mathbf{140} \\ 5y &=& 140 - 7x \\ y &=& \dfrac{140 - 7x}{5} \\ y &=& \dfrac{140 - 5x-2x}{5} \\ y &=& 28 - x - \underbrace{\dfrac{2x}{5}}_{=a} \\ y &=& 28 - x - a & a&=&\dfrac{2x}{5} \\ & & & 5a&=&2x \\ & & & 2x&=&5a \\ & & & x&=&\dfrac{5a}{2} \\ & & & x&=&\dfrac{4a+a}{2} \\ & & & x&=&2a+\underbrace{\dfrac{a}{2}}_{=b} \\ & & & x&=&2a+b & b&=& \dfrac{a}{2} \\ & & & & & & 2b&=& a \\ & & & & & & \mathbf{a}&=& \mathbf{2b} \\ & & & x&=&2(2b)+b \\ & & & \mathbf{x}&=&\mathbf{5b} \\ y &=& 28 - 5b - 2b \\ \mathbf{y} &=& \mathbf{28 - 7b} \\ \hline \end{array}\)

 

The possible combinations of packages:

\(\begin{array}{|c|r|r|} \hline b & x=5b & y = 28 - 7b \\ \hline 1 & 5 & 21 \\ 2 & 10 & 14 \\ 3 & 15 & 7 \\ \hline \end{array}\)

 

1.   5 packages of hotdogs and 21 packages of buns

2. 10 packages of hotdogs and 14 packages of buns

3. 15 packages of hotdogs and 7 packages of buns

 

laugh

Jan 29, 2020

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