A triangular plot of land has its three corners at A(0,0), B(30,0) and C(20,40), where the coordinates are measured in metres from a fixed origin on a map.
a. (i) Calculate the exact area of the plot in square metres.
b. (ii) The owner plans to sell the land at the rate of ₹ 850 per square metre. Determine the selling price of the entire plot.