там может не все понятно во втором быть. корявый почерк(

3 7/9 - 142/9 =34/9 - 142/9 = -108/9 = -12

(3 1/3 - 4,7) : 1/90 = (10/3 - 47/10) *90 = 300 - 47*9 = 300 - 423 = - 123

(1 1/4 - 95/32) : 5/96 = (5/4 - 95/32) * 96/5 = 96/4 - 95 * 96 / 32 * 5 = 24 - 3 * 19 = 24 - 57 = -33

(88 4/5 - 56 49/50): 3,7 = (88 40/50 - 56 49/50) * 10/37 = (4440/50 - 2849/50) * 10/37 =

= (1591/50)*10/37 = 1591 /5*37 = 8.6