甲:乙丙=1:3,甲占总数=1/(1+3)=1/4
乙:甲丙=2:5,乙占总数=2/(2+5)=2/7
丙占总数=1-1/4-2/7=13/28
丙比甲重12,
总数:12÷(13/28-1/4)=56
甲:56×1/4=14
乙:56×2/7=16
丙:14+12=26
甲:乙丙=1:3,甲占总数=1/(1+3)=1/4
乙:甲丙=2:5,乙占总数=2/(2+5)=2/7
丙占总数=1-1/4-2/7=13/28
丙比甲重12,
总数:12÷(13/28-1/4)=56
甲:56×1/4=14
乙:56×2/7=16
丙:14+12=26