To be able to find the answer, you have to consider that 1 km is equal to 1000 meters and with this, you can use rule of three to find the kilometers in 8000 meters:
1 km → 1000 meters
x ← 8000 meters
x=(1*8000)/1000=8 km
According to this, the answer is that Donna swims 8 km each week.
