Question

4 ounce bottle of medicine contains 20 doses how many doses are in a 13 ounce of all of the same medicine

Answer 1

65 doses because each ounce is 5 doses so 13 times 5 is 65

Answer 2

$\bf \begin{array}{ccllll} ounces&doses\\ \textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\ 4&20\\ 13&x \end{array}\implies \cfrac{4}{13}=\cfrac{20}{x}$

solve for "x"