2.4×(3/4+2/3)-3.2 =12/5×3/4+12/5×2/3-16/5 =9/5+8/5-16/5 =1/5
2/15 ÷ (1.1-3/4)+3/7×3/4 =2/15×20/7+9/28 =8/21+9/28 =59/84
(5.6-1/5)×2/9+0.75 ÷ 1/6 =27/5×2/9+3/4×6 =6/5+9/2 =57/10
(2+3/5) ÷ (2.2+1/10)+2/9×18/23 =13/5×10/23+4/23 =26/23+4/23 =30/23
(4/7+2/3)×21/8 =4/7×21/8+2/3×21/8 =3/2+7/4 =13/4