so .. in 1foot, there are 12inches... thus, in 15feet, there are 15*12 inches
how many in 3/4 of an inch? well [tex]\bf \begin{array}{ccllll}
feet&inches\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
15&15\cdot 12\\
x&\frac{3}{4}
\end{array}\implies \cfrac{15}{x}=\cfrac{15\cdot 12}{\frac{3}{4}}\implies \cfrac{15}{x}=\cfrac{\frac{15\cdot 12}{1}}{\frac{3}{4}}
\\\\\\
\cfrac{15}{x}=\cfrac{15\cdot 12}{1}\cdot \cfrac{4}{3}\implies \cfrac{15}{x}=\cfrac{15\cdot 12\cdot 4}{3}[/tex]
solve for "x"
