So,
We will have to divide the length the coach wants you to swim by the length of your pool to find how many laps you must swim. However, we need to first convert 3 km to meters by multiplying by 1000 (because 1 km = 1000 m).
3 * 1000 = 3000 m
Now we can divide.
[tex] \frac{3000}{25} = \frac{600}{5}= 120[/tex]
You will need to swim 120 laps (not a realistic number).