To get you started on the algebra, it might help to note that the mathematical curves used to represent Mondrian were

$$
\begin{eqnarray}
y&=&0.5\tan(1.2(x-1)) - 0.3\\
0.5(y-1.5)^2+x^2 &=& 0.6\\
(y-1.6)^2+0.25(x\pm 0.3)^2&=& 0.01\\
y&=&-8(x-1)^3\\
y&=&-2x-2\\
y&=&-4x -2\\
y&=&5x-2 \\
y&=&3x-2
\end{eqnarray}
$$