Consider a rectangular plate of 15 cm x 18 cm in which each side is held at 50⁰C. What will be the temperature at interior nodes, if steady-state two dimensional heat flows in a metal is given by: \(\frac{\partial^2T}{\partial x^2} + \frac{\partial^2T}{\partial y^2} = xy\). Assume square gird of size 3 cm x 3 cm.