8 дробь 1/12-3 дробь 4/15- 1 дробь7/30=(8*12+1)/12 - (3*15+4)/15-(1*30+7)/30=
=97/12-49/15-37/30=97/12-98/30-37/30=97/12-135/30=485/60-270/60=(485-270)/60=
=215/60=43/12
8 ц. 1/12 - 3ц. 4/15 - 1ц. 7/30 = 97/12 - 49/15 - 37/30 = 485/60 - 196/60 - 74/60 = 43/12= 3ц. 7/12
