Помогите решить номер 831
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3 / (1-1/2)=3:1/2=3*2/1=6 ------- (1-1/4) / 1 1/2=3/4:1 1/2=3/4:3/2=3/4*2/3=1/2*1=1/2 ------- (2/3+1/4) / 1 5/6=(8/12+3/12) / 1 5/6=11/12:1 5/6=11/12:11/6=11/12*6/11=1/2 ------- 8 1/3 / (8/9-1/3)=8 1/3 / (8/9-3/9)=25/3:5/9=25/3*9/5=5/1*3/1=15