494 задача.
5 класс
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1)=59 25/64-32 12/64-4 1/64=23 12/64=23 3/16

2)=32 2/45+20 25/45-18 36/45=34-9/45=33 36/45

3)=37 116/144-4 40/144-1 93/144=32 -17/144=31 127/144

4)=40 61/80-7 68/80+25 6/80=58 -1/80=57 79/80