My car has to go for a service in 2 871 km. I drove 1 264 km during the month. How many kilometres before I have to take my car for the service?

Since $1 \text{ cm} = 10 \text{ mm}$, divide by 10.

$$2900 \text{ mm} \div 10 = 290 \text{ cm}$$

Since $1 \text{ m} = 1000 \text{ mm}$, divide by 1000.

$$2900 \text{ mm} \div 1000 = 2.9 \text{ m}$$

$2.9 \text{ m}$ is $2 \text{ m}$ and $0.9 \text{ m}$. Convert $0.9 \text{ m}$ to centimeters ($0.9 \times 100 = 90 \text{ cm}$).
The difference is $\boxed{\text{2900 mm, 290 cm, 2 m 90 cm, or 2.9 m}}$.

: I bought $90 \text{ m}$ of wool. I used $19 \frac{1}{2} \text{ m}$. How much wool do I have left? Write your answer in m.

$$90 \text{ m} - 19.5 \text{ m} = 70.5 \text{ m}$$

You have $\boxed{\text{70.5 m}}$ of wool left.

: Sandra and Sipho travelled $1520 \text{ km}$. Sandra drove $579 \text{ km}$. How far did Sipho drive?

$$1520 \text{ km} - 579 \text{ km} = 941 \text{ km}$$

Sipho drove $\boxed{\text{941 km}}$.

: My car has to go for a service in $2871 \text{ km}$. I drove $1264 \text{ km}$ during the month. How many kilometres before I have to take my car for the service?

$$2871 \text{ km} - 1264 \text{ km} = 1607 \text{ km}$$

You have $\boxed{\text{1607 km}}$ before you have to take your car for service.