1.3/4×3/5+2/5×3/4=1/4x 1/5 x3(1.3+2)=3/20 x3.3=9.9/20=99/2002.8×5/6+2/5÷4=14/5 x 5/6 +2/5 x 1/4=2/5 (7 x 5/6 + 1/4)=2/5(70/12 + 3/12)=2/5 x 73/12=73/30