а) 5/12+11/24=10/24+11/24=21/24=7/8; б) 17/18-7/9=17/18-14/18=3/18=1/6.
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3/25*5=15/25=3/5кг =600гр весят 5 пачек вафель
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(3/8+5/12)*4 =(9/24+10/24)*4=19/24*4=76/24=3 1/6; б) (5/6-2/9):11=(15/18-4/18):11=
=11/18*1/11=1/18
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3/7:30=3/7*1/30=1/70 часть орехов белка съедает за тень
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б) 4 6/17-1 10/17=74/17-27/17=47/17=2 13/17;