Помогите !!!!!!!!!!!!!! плизз!!!!!!!!!!!

Question

Помогите !!!!!!!!!!!!!! плизз!!!!!!!!!!!

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Answer 1

1)=(5/21+2/21)+2/15=7/21+2/15=1/3+2/15=5/15+2/15=7/15
2)=2/35+(3/28+1/28)=2/35+4/28=2/35+1/7=2/35+5/35=7/35=1/5
3)=(7/30+1/30)+(8/45+2/45)=8/30+10/45=4/15+2/9=12/45+10/45=22/45
4)(5/24+1/24)+(11/60+13/60)=6/24+24/60=1/4+2/5=5/20+8/20=13/20