Đáp án + Giải thích các bước giải:

`1) (2/3 + 1/4) . 1/2 + 1/3 . (1/2 + 3/4)`

`= (8/12 + 3/12) . 1/2 + 1/3 . (4/8 + 6/8)`

`= 11/12 . 1/2 + 1/3 . 10/8`

`= 11/24 + 10/24`

`= 21/24`

`= 7/8`

`2) (3/5 - 1/2) . 4/3 + 3/5 . (11/3 + 1/2)`

`= (6/10 - 5/10) . 4/3 + 3/5 . (22/6 + 3/6)`

`= 1/10 . 4/3 + 3/5 . 25/6`

`= 4/30 + 75/30`

`= 79/30`

`3) (3/2 - 1/7) . 3/4 + 5/2 . (1/7 + 3/4)`

`= (21/14 - 2/14) . 3/4 + 5/2 . (4/28 + 21/28)`

`= 19/14 . 3/4 + 5/2 . 25/28`

`= 57/56 + 125/56`

`= 182/56`

`= 91/28`

`4) 2/3 . (1/2 + 3/4) + 1/2 . (3/4 + 2/3)`

`= 2/3 . (2/4 + 3/4) + 1/2 . (9/12 + 8/12)`

`= 2/3 . 5/4 + 1/2 . 17/12`

`= 10/12 + 17/24`

`= 20/24 + 17/24`

`= 37/24`

`5) (1/2 + 3/5) . (-4/3) + (4/5 + 4/3) . 5/3`

`= (5/10 + 6/10) . (-4/3) + (12/15 + 20/15) . 5/3`

`= 11/10 . (-4/3) + 32/15 . 5/3`

`= -44/30 + 160/45`

`= -22/15 + 160/45`

`= -66/45 + 160/45`

`= 94/45`

`6) 1/6 . (2/3 + 5/2) + (5/2 + 1/6)`

`= 1/6 . (4/6 + 15/6) + (15/6 + 1/6)`

`= 1/6 . 19/6 + 16/6`

`= 19/36 + 16/6`

`= 19/36 + 96/36`

`= 115/36`