[tex]\bf 1:1.618\iff \cfrac{1}{1.618}\cfrac{\leftarrow \textit{small side=width}}{\leftarrow \textit{longer side=length}}\\\\
-----------------------------\\\\
\textit{now, what if the length is 35?}\to \cfrac{1}{1.618}=\cfrac{w}{\boxed{35}}[/tex]
solve for "w" to get the width
what's the area of a rectangle? length * width, or lw