a. Solve the following Linear Programming problem and obtain optimum solution. (X1, X2, X3, X4 >=0) b. You have been informed that variables X3 and X4 are integer variables. Now, solve this mix integer programming problem and obtain optimum solution. (X1, X2 >=0, X3, X4 - integer) Max Z = 25X1+32X2+36X3+20X4 Subject to: 6X1+7X2+4X3+2X4<=950 3X1+4X2+8X3+3X4 <= 900 7X1+7X2+8X3+9X4 <= 2000