1) 7 цел. пять шестых-6 цел. три восьмых+3 цел. семь девятых=? решить по действиям - (4 цел. три четвёртых - 3,75) + (9 цел. пять шестых - 3 цел. семнадцать восемнадцатых) =

№1

7 5/6 - 6 3/8 + 3 7/9 = 377/72 = 5 17/72.

1) 7 5/6 - 6 3/8 = 47/6 - 51/8 = (47 * 4) / (6 * 4) - (51 * 3) / (8 * 3) = 188/24 - 153/24 = 35/24 = 1 11/24;

2) 1 11/24 + 3 7/9 = 35/24 + 34/9 = (35 * 3) / (24 * 3) + (34 * 8) / (9 * 8) = 105/72 + 272/72 = 377/72 = 5 17/72.

№2

- (4 3/4 - 3,75) + (9 5/6 - 3 17/18) = 1 22/45.

1) 4 3/4 - 3,75 = 19/4 - 35/100 = (19 * 25) / (4 * 25) - 35/100 = 475/100 - 35/100 = 440/100 = 44/10 = 4 4/10 = 4 2/5;

2) 9 5/6 - 3 17/18 = 59/6 - 71/18 = (59 * 3) / (6 * 3) - 71/18 = 177/18 - 71/18 = 106/18 = 5 16/18 = 5 8/9;

3) - 4 2/5 + 5 8/9 = - 44/10 + 53/9 = (-44 * 9) / (10 * 9) + (53 * 10) / (9 * 10) = - 396/90 + 530/90 = 134/90 = 1 44/90 = 1 22/45.