A company manufactures two products x and y. Each product has to be processed in three departments: welding, assembly and painting. Each unit of x spends 2 hours in the welding department, 3 hours in assembly and 1 hour in painting. The corresponding times for a unit of y are 3, 2 and 1 hours respectively. The employee hours available in a month are 1500 for the welding department, 1500 in assembly and 550 in painting. The contribution to profits are rs100 for product x and rs120 for product y. What is the objective function (z) to be maximised in this linear programming problem.