One song download costs $2 and one movie download costs $11.
Step-by-step explanation:
Let,
Price of one song download = x
Price of one movie download = y
According to given statement;
8x+9y=115 Eqn 1
15x+9y=129 Eqn 2
Subtracting Eqn 1 from Eqn 2
![(15x+9y)-(8x+9y)=129-115\\15x+9y-8x-9y=14\\7x=14](https://tex.z-dn.net/?f=%2815x%2B9y%29-%288x%2B9y%29%3D129-115%5C%5C15x%2B9y-8x-9y%3D14%5C%5C7x%3D14)
Dividing both sides by 7
![\frac{7x}{7}=\frac{14}{7}\\x=2](https://tex.z-dn.net/?f=%5Cfrac%7B7x%7D%7B7%7D%3D%5Cfrac%7B14%7D%7B7%7D%5C%5Cx%3D2)
Putting x=2 in Eqn 1
![8(2)+9y=115\\16+9y=115\\9y=115-16\\9y=99](https://tex.z-dn.net/?f=8%282%29%2B9y%3D115%5C%5C16%2B9y%3D115%5C%5C9y%3D115-16%5C%5C9y%3D99)
Dividing both sides by 9
![\frac{9y}{9}=\frac{99}{9}\\y=11](https://tex.z-dn.net/?f=%5Cfrac%7B9y%7D%7B9%7D%3D%5Cfrac%7B99%7D%7B9%7D%5C%5Cy%3D11)
One song download costs $2 and one movie download costs $11.
Keywords: linear equation, elimination method
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