4 2/9×2 4/7+1 2/9×2 4/7=2 4/7×(4 2/9+1 2/9)=2 4/7×5 4/9=
=18/7×49/9=(9*2)/7 × (7*7)/9=2/1×7/1=2×7=14
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2 5/6×6 2/3+3/10×6 2/3-6 2/3×1 1/3=6 2/3×(2 5/6+3/10-1 1/3)=
=6 2/3×(2 25/30+9/30-1 10/30)=6 2/3×1 24/30=6 2/3×1 4/5=
=20/3×9/5=4/1×3/1=4×3=12