Is this simple ratio and proportion?

Electricity and Magnetism Level 3

For the given circuit above, resistors \(X\) and \(Y\) have fixed values, and the range of resistance of the variable resistor is 0 to 1000 ohms. If the variable resistor is set at \( 0\:\Omega\), \(V_A = 27\: V \), and \( V_A = 52\: V \) when it is set to \(1000 \:\Omega\). Determine at what resistance (in ohms) must the variable resistor be set such that the output voltage measured between \(A\) and ground is \( 42 \: V\).

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