Solid metallic spheres of diameters 12 cm, 16 cm and 20 cm respectively, are melted to form a single solid sphere. Find the radius of the resulting sphere.

On a graph paper, plot the triangle ABC whose vertices are at the points A(4, 2), B(4, -1) and C(6, 3). On the same graph, draw the image of the triangle ABC under reflection in the line x = 2. Mark any two points on the graph paper which are invariant under this reflection. Also, write the co-ordinates of points marked.

A dealer from Banaras supplies goods/services, worth ₹ 1,00,000 to a dealer in Bangalore at 30% discount. If the rate of GST is 5%, find the amount of bill in Bangalore.