I bought

I bought two bottles of alcohol and two sanitizers for 126 pesos. How much is a bottle of alcohol if the cost of alcohol is five times the cost of sanitizer?

Correct answer:

a =  52.5

Step-by-step explanation:

$$\begin{gathered} 2a+2s=126 \\ a=5s \\ 2\cdot a+2\cdot s=126 \\ a=5\cdot s \\ 2a+2s=126 \\ a-5s=0 \\ Row2-\frac{1}{2}\cdot Row1\to Row2 \\ 2a+2s=126 \\ -6s=-63 \\ s=\frac{-63}{-6}=10.5 \\ a=\frac{126-2s}{2}=\frac{126-2\cdot 10.5}{2}=52.5 \\ a=\frac{105}{2}=52.5 \\ s=\frac{21}{2}=10.5 \end{gathered}$$

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