=3/4*5/2=15/8=1 7/8
=30/7*10/11=300/77=3 69/77
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4 1/3-(2/5)²=4 1/3-4/25=4 25/75-4/75=4 21/75
4 21/75+3 1/75=7 22/75
7 22/75:4/75=547/75*75/4=136 3/4
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3 17/18х=5/18-3/18
х=1/9*18/71
х=2/71