Bài 1) Tính tổngg

a) ( 1/4 + -5/13) + (2/4 + -8/13 + 3/4)

b) (21/31 + -16/7) + (44/53 + 10/31) + 9/53

c) 31/23 - (7/32 + 8/23) - (-7/32 - 1/47) + 2/141

a) `(1/4 - 5/13) + (2/4 - 8/13 + 3/4)`

`= (-7/52) + (21/52)`

`= 14/52`

`= 7/26`

b) `(21/31 - 16/7) + (44/53 + 10/31) + 9/53`

`= (-407/217) + (2214/16583) + (477/5309)`

`= -3555/5309`

c) `31/23 - (7/32 + 8/23) - (-7/32 - 1/47) + 2/141`

= `31/23 - (161/736) - (233/736) + 2/141`

= `31/23 - 394/736 + 2/141`

= `(321/23) - (197/368)`

= `(7376/368) - (197/368)`

= `7179/368`