Bài 1:
a) `7/3 : 14/15 - 9/4`
`= 7/3 . 15/14 - 9/4`
`= 5/2 -9/4`
`= 10/4 - 9/4`
`= 1/4`
b) `15 3/7 - ( 8/9 + 7 3/7)`
`= 15+ 3/7 - ( 8/9 + 7 + 3/7)`
`= 15 + 3/7 - 8/9 - 7 - 3/7`
`= (15 -7) + (3/7 - 3/7) - 8/9`
`= 8 - 8/9`
`=64/9`
c) `5/9 . 7/13 -30/23 + 6/9 . 5/13 + 7/23`
`= 7/9 . 5/13 - ( 30/23 - 7/23) + 6/9 . 5/13`
`= 5/13 ( 7/9 + 6/9) - 1`
`= 5/13 . 13/9 -1`
`=5/9 - 9/9`
`= -4/9`
d) `2022 - 40% + 3/5 . (-1)^2007`
`= 2022 - 2/5 + 3/5 . (-1)`
`= 2022 -2/5 + (-3/5)`
`= 2022 + (-3/5 - 2/5)`
`= 2022 + (-1)`
`= 2021`
