Question

A salad dressing is made by combining 2 part vinegar 5 part oil. How much ounces of oil should be mixed with 9 ounces of vinegar?

Answer 1

$\bf \begin{array}{ccll} vinegar&oil\\ \cline{1-2} 2&5\\ 9&x \end{array}\implies \cfrac{2}{9}=\cfrac{5}{x}\implies 2x=45\implies x=\cfrac{45}{2}\implies x=22\frac{1}{2}$