so the ratio is at ¼ : 12, namely the drawing has ¼ inch to an actual 12 feet.
so, what would it be for an actual 15 feet on the drawing then?
[tex]\bf \begin{array}{ccll}
\stackrel{inches}{drawing}&\stackrel{feet}{actual}\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
\frac{1}{4}&12\\\\
d&15
\end{array}\implies \cfrac{\quad \frac{1}{4}\quad }{d}=\cfrac{12}{15}\implies \cfrac{\quad \frac{1}{4}\quad }{\frac{d}{1}}=\cfrac{12}{15}
\\\\\\
\cfrac{1}{4}\cdot \cfrac{1}{d}=\cfrac{12}{15}\implies \cfrac{1}{4d}=\cfrac{12}{15}\implies 15=48d\implies \cfrac{15}{48}=d\implies \cfrac{5}{16}=d[/tex]
