1. 5/9 + 1 5/7 × ( 4 2/3 - 2 5/8) ÷ 1 3/4 = 5/9 +12/7*(14/3-21/8) : 7/4 = 5/9+12/7*(112/24-63/24) : 7/4 = 5/9+12/7*49/24 : 7/4 =5/9+7/12 : 7/4 = 5/9+7/12 : 7/4 = 5/9+1/3=5/9+3/9=8/9
2. 2 - 3 1/7 × ( 2 - 1 9/11) ÷ 8/21 = 2-11/7*(22/11-20/11) : 8/21 = 2-11/7*2/11 : 8/21 = 2 - 2/7 : 8/21 = 2 - 3/4 = 8/4 - 3/4 = 5/4 = 1 1/4