Giúp mình làm bài 1,2 nhé

#wheijx.

`1.`

`a)` `2024 xx 2025 xx 2026 xx 2027 xx 2028 xx ( 1288 - 56 xx 23 )`

`= 2024 xx 2025 xx 2026 xx 2027 xx 2028 xx ( 1288 - 1288 )`

`= 2024 xx 2025 xx 2026 xx 2027 xx 2028 xx 0`

`= 0`

`b)` `1/5 + 5/9 + 4/5 + 1/9 + 3/9`

`= ( 1/5 + 4/5 ) + ( 5/9 + 1/9 + 3/9 )`

`= 5/5 + 9/9`

`= 1 + 1`

`= 2`

`c)` `1/3 + 1/6 + 4/3 + 2/6 + 2/3 + 5/6`

`= ( 1/3 + 4/3 + 2/3 ) + ( 1/6 + 2/6 + 5/6 )`

`= 7/3 + 8/6`

`= 7/3 + 4/3`

`= 11/3`

`2.`

`( 23 xx 27 - 27 xx 20 ) + ( 20 xx 18 - 18 xx 17 )`

`= 27 xx ( 23 - 20 ) + 18 xx ( 20 - 17 )`

`= 27 xx 3 + 18 xx 3`

`= ( 27 + 18 ) xx 3`

`= 45 xx 3`

`= 135`