Найдите значение выражения: а) 1/2 - 4/45 + 13/15 = ? б) 14/15 + 11/12 - 1 7/10 = ? в) 3 7/20 - 2 2/7 + 3/28 = ? напишите без х, и запишите сразу решение.

А) 1/2 - 4/45 + 13/15 = (45•1)/(2•45)- (4•2)/(45•2)+ (13•6)/(15•6)= 45/90- 8/90+ 78/90= 78/90- 8/90+ 45/90= 70/90+ 45/90= 115/90= 1 25/90= 1 5/18. (Сократили на 5; 25:5=5; 90:5=18). ➡️➡️➡️ б) 14/15 + 11/12 - 1 7/10 = (14•4)/(15•4)+ (11•5)/(12•5)- (10•1+7)/10= 56/60+ 55/60 -(17•6)/(10•6)= 111/60- 102/60= 9/60= 3/20 (сократили на 3; 9:3=3; 60:3=20). ➡️➡️➡️ в) 3 7/20 - 2 2/7 + 3/28 = (20•3+7)/20- (7•2+2)/7+ 3/28= 67/20- 16/7+ 3/28= (67•7)/(20•7)- (16•20)/(7•20)+ (3•5)/(28•5)= 469/140 - 320/140+ 15/140= 149/140= +15/140= 164/140= 1 24/140= 1 6/35; (сократили 24:4=6; 140:4=35).

А) 1/2 - 4/45 + 13/15 = <br />45/90 - 8/90 + 78/90 = 15/90 = 23/18 = 1 5/18 [1 целая 5/18].<br /><br />б) 14/15 + 11/12 - 1 7/10 =<br />56/60 + 55/60 - 102/60 =<br />(111-102)/60 = 9/60 = 3/20.<br /><br />в) 3 7/20 - 2 2/7 + 3/28 =<br />469/140 - 320/140 + 15/140 = (469-320+15)/140 = 164/140 = 41/35 = 1 6/35 [одна целая 6/35].<br />