4%소금물을y,9%소금물을x라하면x+y=500(6%의소금물)-①,4%소금은4y/100,9%소금은9x/100.따라서4y/100+9x/100=30(6%의소금)-②.①,②식을연립하여계산하면x=200
당신은 어느 그룹입니까?