I'm designing a layout and I would like to use four golden ratio rectangles. The total width of the layout is 960px. How do I find the height (x)? Below is a diagram of the layout.

I'm designing a layout and I would like to use four golden ratio rectangles. The total width of the layout is 960px. How do I find the height (x)? Below is a diagram of the layout.

Finding the required height amounts to expressing $a$ and $c$ in terms of the height $h = a+b$. I will do this below; denote with $\phi$ the golden ratio.
We have that $\dfrac h a =\phi$, i.e. $a = \dfrac h \phi$. Now $d = \dfrac h2$, and $\dfrac c d = \phi$.
Using some trivial algebra, we obtain:
$$c = \phi d = \frac\phi2 h$$
Thus we have reduced to solving the equation:
$$960 = 2a + c = \left(\frac2\phi+\frac\phi 2\right)h$$
In conclusion, $h = \dfrac{960}{\frac2\phi+\frac\phi 2} \approx 469.42$.