Đáp án `+` Giải thích các bước giải:

a) `7/30 + (-12)/37 + 23/30 + (-25)/37`

`= (7/30 + 23/30) + ((-12)/37 + (-25)/37)`

`= 30/30 + (-37)/37`

`= 1 + (-1)`

`= 0.`

b) `1/2 + 13/49 - 4/9 + 6/19 + 5/18`

`= (1/2 - 4/9 + 5/18) + (13/19 + 6/19)`

`= (9/18 - 8/18 + 5/18) + 19/19`

`= 1/3 + 1`

`= 4/3.`

d) `4/3 + (-11)/31 + 3/10 - 20/31 - 2/5`

`= (-11/31 - 20/31) + (3/10 - 2/5) + 4/3`

`= (-31)/31 + (3/10 - 4/10) + 4/3`

`= -1 + (-1)/10 + 4/3`

`= -30/30 + (-3)/30 + 40/30`

`= 7/30.`

e) `5/7 . 5/11 + 5/7 . 2/11 - 5/7 . 14/11`

`= 5/7 . (5/11 + 2/11 - 14/11)`

`= 5/7 . (-7)/11`

`= -5/11.`