Bài `2 : `

`a) ``456 + 675 + 244 - 375`

`= (456 + 244) + (675 - 375)`

`= 700 + 300`

`= 1000`

`b)` `2667 + 590 - 567 + 310`

   `= (2667 - 567) + (590 + 310)`

   `= 2100 + 900`

   `= 3000`

`c)` `1789 × 5467 × (460 - 230 × 2)`

    `= 1789 × 5467 × (460 - 460)`

    `= 1789 × 5467 × 0`

    `= 0`

`d)` `700 + 197 - 200 + 203`

    `= 700 - 200 + (197 + 203)`

    `= 500 + 400`

    `= 900`

`e)` `(237 + 113) ÷ ( 419 - 209 × 2)`

    `= 450 ÷ (419 - 418)`

    `= 450 ÷ 1`

    `= 450`

Bài` 3:`

`A )`

`11/20 × 5/8 + 3/8 × 11/20`

`= 11/20 × (5/8 + 3/8)`

`= 11/20 × 1`

`= 11/20`

`B )`

`2/9 ÷ 6/7 + 7/9 ÷ 6/7`

`= (2/9 + 7/9) ÷ 6/7`

`= 1 ÷ 6/7`

`= 7/6`