3/20÷0.2×2/3 =3/20*5*2/3=1/2 4/9÷8/3÷4/9 =4/9÷4/9÷8/3=1*3/8=3/85/21÷10/7×3/4=5/21*7/10*3/4=1/2*1/4=1/86/17÷12/17÷7/9 =6/17*17/12*9/7=1/2*9/7=9/14