so, the mixture is 50oz, 10 of those is alcohol, the rest is water, or 40oz
what's 40 in percentage of 50? well, if we take the 50 to be the 100%, then [tex]\bf \begin{array}{ccllll}
amount&\%\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
50&100\\
40&x
\end{array}\implies \cfrac{50}{40}=\cfrac{100}{x}[/tex]
how much is 10 in percentage of 50? well [tex]\bf \begin{array}{ccllll}
amount&\%\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
50&100\\
10&x
\end{array}\implies \cfrac{50}{10}=\cfrac{100}{x}[/tex]
solve for "x" in each
