ABC26GN1378 · Square Roots and Cube Roots

$$\begin{aligned} & \text { Let } \sqrt{\frac{x}{169}}=\frac{54}{39} \text {. Then, } \frac{\sqrt{x}}{13}=\frac{54}{39} \Leftrightarrow \sqrt{x}=\left(\frac{54}{39} \times 13\right)=18 \\ & \Leftrightarrow \quad x=(18)^{2}=324 . \end{aligned}$$