Verified answer

3) х+27 8/9=52

х=52-27 8/9

х=51 9/9-27 8/9

х=24 1/9

9) х-31 4/21=13 9/28

х=13 9/28+31 4/21

х=13 27/84+31 16/84

х=44 43/84

10) 81 5/6-х=79 3/4

х=81 5/6-79 3/4

х=81 10/12-79 9/12

х=2 1/12