Помогите решить: (/-это дробь)

67) - 6∙ (-2) : (-4) ∙3

68) - 15∙4-48

69) 1-6/27

70) (9-22/3∙21/7) ∙21/46

71) 51/6 - 33/4

72) 13/5∙21

-6∙ (-2) : (-4) ∙3=12 / (-12) = - 1

-15∙4-48=-60-48=-108

1-6/27 = 27*1-6*1/27=27-6/27=21/27=7/9

(9-22/3∙21/7) ∙21/46=-5 43/46

1) 22/3*21/7=462/21=22

2) 9-22=-13

3) - 13*21/46 = - 13*21/46=-273/46=-5 43/46

51/6 - 33/4=51*2-33*3/12=102-99/12=3/12=1/4

13/5∙21=13*21/5=273/5=54 3/5