`\color{ #7EC8E3}{⋆˚⟡˖ ࣪ n}``\color{#87CEEB}{e}``\color{#00BFFF}{c}``\color{#1E90FF}{h}``\color{#4682B4}{o}``\color{#5F9EA0}{i}``\color{#6495ED}{l}``\color{#4169E1}{i}``\color{#4682B4}{n}``\color{#00BFFF}{h}``\color{#1E90FF}{c}``\color{#87CEFA}{u}``\color{#B0E0E6}{te⋆˚⟡˖ ࣪}`

Bài `2`: 

`8` `\text{ m }` `7 \text{ dm}` `=` `8.7` `\text{ m}`

`4` `\text{ m }` `8 \text{ cm}` `=` `4.08` `\text{ m}`

`5` `\text{ cm }` `6` `\text{ mm}` `=` `5.6` `\text{ cm}`

`6` `\text{ kg }` `75` `\text{ g}` `=` `6.075` `\text{ kg}`

`215` `\text{ cm}` `=` `2.15` `\text{ m}`

`76` `\text{ mm}` `=` `7.6` `\text{ cm}`

`9` `\text{ mm}` `=` `0.9` `\text{ cm}`

`6100` `\text{ g}` `=` `6.1` `\text{ kg}`

Bài `3`: 

`6` `\text{ l }` `260` `\text{ ml}` `=` `6.26` `\text{ l}`

`5` `\text{ l }` `75` `\text{ ml}` `=` `5.075` `\text{ l}`

`3452` `\text{ ml}` `=` `3.452` `\text{ l}`

`750` `\text{ ml}` `=` `0.75` `\text{ l}`

Bài `4`: 

`8` `\text{ m}^2` `75` `\text{ dm}^2``=` `8.75` `\text{ m}^2`

`3` `\text{ m}^2` `6` `\text{ dm}^2` `=` `3.06` `\text{ m}^2`

`120` `\text{ dm}^2` `=` `1.2` `\text{ m}^2`

`4` `\text{ dm}^2` `25` `\text{ cm}^2` `=` `4.25` `\text{ dm}^2`

`2` `\text{ dm}^2` `5 \text{ cm}^2` `=` `2.05` `\text{ dm}^2`

`85` `\text{ cm}^2` `=` `0.85` `\text{ dm}^2`

Bài `5`:

`5` `\text{ km}^2` `=` `500 \text{ ha}`

`30 000` `\text{ ha}` `=` `300` `\text{ km}^2`

`4` `\text{ km}^2` `5 \text{ ha}` `=` `405 \text{ ha}`

`127500` `\text{ ha}` `=` `1275` `\text{ km}^2`

Bài `6`:

Diện tích khu đất bác Nha dùng để xây dựng khu chăn nuôi là:

`3` `\text{ ha}` `\times` `(1)/6` `=` `(1)/2` `\text{ ha}`

Đổi `(1)/2` `\text{ ha}` sang mét vuông:

`(1)/2` `\text{ ha}` `=` `(1)/2` `\times` `10000` `\text{ m}^2` `=` `5000` `\text{ m}^2` 

Vậy, bác Nha đã dùng `5000` `\text{ m}^2` để xây dựng khu chăn nuôi.