maximize 1500x1+ 5000x2 + 5000x3 + 4000x4 subject to x1+1.5x2 + 2x3 +x4<=45 and x1+x2+x3+x4<=35 and x1>=2x2 and x2>=x3 and x3>=8x4 and x1>=0 and x2 >=0 and x3>=0 and x4 >=0