6. Five marks example problems II

A real estate owner had two plots, a square plot of side \(39 \ m\) and a rectangular plot of dimensions \(100 \ m\) length and \(64 \ m\) breadth. He sells both of these plots and acquires a new square plot of the same area. What is the length of side of his new plot?

 

Side length of a new plot \(=\)  \(m\)