Show that the decision version of the knapsack problem is np-complete. (hint: in your reduction, make use of the partition problem: given n positive integers, partition them into two disjoint subsets with the same sum of their elements. the partition problem is np-complete.)

An open feedwater heater operates at steady state with liquid entering at inlet 1 with t? = 40°c and pl = 1 .2 mpa. water vapor att2-200°c and p2 = 1.2 mpa enters at inlet 2. saturated liquid water exits with a pressure of pa 1.2 mpa. neglect heat transfer with the surroundings and all kinetic and potential energy effects, determine the mass flow rate of steam at inlet 2 if the mass flow rate of liquid water at inlet 1 is given as 2 kg/s.