Maximize[500 x1+700 x2+1200 x3+400 x4+300 x5,{5 x1+7 x2+10 x3+3 x4+4 x5<=20,0<=x1<=1,0<=x2<=1,0<=x3<=1,0<=x4<=1,0<=x5<=1},{x1,x2,x3,x4,x5},Integers]