(7/45+7/30+4/5):(2-1/3-1/2)=?

(7/45+7/30+4/5):(2-1/3-1/2)= =(14/90+21/90+72/90):(12/6-2/6-3/6)= =107/90:7/6=(107*6):(90*7)=642/630=1 2/105

(7/45 + 7/30 + 4/5) : (2 - 1/3 - 1/2) = 1 целая 2/105 1) 7/45 + 7/30 = 14/90 + 21/90 = 35/90  2) 35/90 + 4/5 = 35/90 + 72/90 = 107/90 3) 2 - 1/3 = 1 целая 3/3 - 1/3 = 1 целая 2/3 4) 1 целая 2/3 - 1/2 = 1 целая 4/6 - 3/6 = 1 целая 1/6 5) 107/90 : 1целая 1/6 = 107/90 : 7/6 = 107/90 * 6/7 = (107*1)/(15*7) = 107/105 = 1 целая 2/105 Пояснения: Общий знаменатель 90 90 : 45 = 2 - доп.множ. к 7/45 = (7*2)/(45*2) = 14/90 90 : 30 = 3 - доп.множ. к 7/30 = (7*3)/(30*3) = 21/90 90 : 5 = 18 - доп.множ. к 4/5 = (4*18)/(5*18) = 72/90 2/3 = 4/6 - доп.множ. 2 1/2 = 3/6 - доп.множ. 3 1 целая 1/6 = (1*6+1)/6 = 7/6 90 в знаменателе и 6 в числителе сократили на 6