x×9=28,2-30×(-14,6)-5,4

1)3/7+1/6+5/14=6/14+5/14+1/6=11/14+1/6=33/42+7/42=40/42=20/21
2)5/12+2/9+1/18=5/12+4/18+1/18=5/12+5/18=15/36+10/36=25/36
3)1/2+1/3+1/9=1/2+3/9+1/9=1/2+4/9=9/18+8/18=17/18