In a meter Bridge experiment resistance x is connected in the right...

In a meter Bridge experiment resistance $x$ is connected in the right gap. When ${R}_{1}$ and ${R}_{2}$ are connected in the left gap separately the balance points are $40cm$ and $50cm$ respectively from the left end. Now if both ${R}_{1} \text{ and } {R}_{2}$ are connected in series in the left gap with $x$ in the right gap then what will be the new balance point from the left end (in $cm$)?