Calculate width and height of rectangle containing given area and conforming to given ratio. My algebra is so rusty, this should be an easy one!
The area of a rectangle is
$$A = W \times H$$
If you're given $A$ (say $150$) and a ratio of $W:H$ (say $3:2$) how can you calculate $W$ and $H$?

I was looking for an answer for the same question. It's just that the other posts are kind of too complicated for me. I see it this way:
If you have given a width $a$ and a height $b$ and you know the $\textsf{area}$. You want to stretch each side with a fixed ratio of $x$ until you get the final size of the area. So you stretch $a$ with $x$ and $b$ with $x$ equals the $\textsf{area}$.
$$\begin{align*}
(a\cdot x)\cdot(b\cdot x)&=\textsf{area}\\\\
(a\cdot b)\cdot x^2&=\textsf{area}\\\\
x^2&=\frac{\textsf{area}}{a\cdot b}\\\\
x&=\sqrt{\frac{\textsf{area}}{a\cdot b}}
\end{align*}$$
$x$ is the ratio you are stretching. So you can multiply $x$ by $a$ and $b$ to get the new size of $a$ or $b$.
