The first and third are correct. They are equal.
The second is incorrect. This is because 1800 meters = 1.8 km (not 18 km). The answer you should have is a "less than sign" because 1.8 km is smaller than 18 km.
To go from meters to kilometers, you move the decimal point 3 spots to the left. This is the same as dividing by 1000.
To go from kilometers to meters, you move the decimal point 3 spots to the right. This is the same as multiplying by 1000.
