Jason has 43 stamps. Some are worth 15 cents and some are worth 20 cents. If their total value is $7.50, how many of each kind does he have?

Guest Jan 24, 2020

#1**+3 **

**Jason has 43 stamps. Some are worth 15 cents and some are worth 20 cents. If their total value is $7.50, how many of each kind does he have?**

\(\text{Let stamps with worth $20$ cents $= x$ }\\ \text{Let stamps with worth $15$ cents $= y$ } \)

\(\begin{array}{|rcll|} \hline x+y &=& 43 \\ \mathbf{y} &=& \mathbf{43-x} \\ \hline \end{array}\)

\(\begin{array}{|rcll|} \hline 20x+15y &=& 750 \quad | \quad \mathbf{y=43-x} \\ 20x+15(43-x)&=& 750 \\ 20x+15*43-15x &=& 750 \\ 20x+645-15x &=& 750 \\ 5x +645 &=& 750 \\ 5x &=& 750 - 645 \\ 5x &=&105 \quad | \quad : 5 \\ \mathbf{x} &=& \mathbf{21} \\\\ \mathbf{y} &=& \mathbf{43-x} \\ y &=& 43-21 \\ \mathbf{y} &=& \mathbf{22} \\ \hline \end{array}\)

Jason does have **21 **stamps with worth of **20 **cents and

he does have **22 **stamps with worth of **15 **cents.

heureka Jan 24, 2020