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 - 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