乙:丙=16:21,设丙=21x,乙=16x,
甲:乙=甲:16x=2:3,得到甲=16x * 2/3 = 32x/3
所以
甲:乙:丙 = 32x/3 :16x :21x
约分
甲:乙:丙 = 32/3 :16 :21 = 32 :48 :63