5/6*3/5-5/12*4/15, 7/18*9/14+1/3*6/7,9/20*2/3+5/14*7/25,3 3/4*2/5-3 6/25*5/27, 2 2/5*5/6-3/4* 1 2/3

5/6×3/5=1/2
5/12×4/15=1/9
1/2-1/9=9/18-2/18=7/18

7/18×9/14=1/4
1/3×6/7=2/7
1/4+2/7=7/28+8/28=15/28

9/20×2/3=3/10
5/14×7/25=1/10
3/10+1/10=4/10=2/5

3 3/4×2/5=15/4×2/5=3/2
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3 6/25×5/27=81/25×5/27=3/5
3/2--3/5=15/10-6/10=9/10

2 2/5×5/6-3/4×1 2/3=
12/5×5/6=2
3/4×5/3=5/4=1 1/4
2-1 1/4=3/4