?????????????? "solving system" ?????????????... 1. x+y=200, so y=200-x, or x=200-y... 2. log(0.5x/0.3y)=0.19, so (0.5x/0.3y)=10^0.19=1.548816619... 0.5*(200-y)/0.3y=1.548816619... (200-y)/0.3y=3.097633238... 200-y=0.3y*3.097633238... 200-y=0.929289971y... 1.929289971y=200... y=200/1.92928997=103.6650804... x=200-y=96.3349196