Answer:
Anneke will swim 20 lengths in the 500-meter event,
which means each length of the pool is = 500/20
= 25m
also since Anneke can swim one length in 26.4 seconds on average
hence her average speed is = 25/26.4 m/s
hence after a seconds,
the distance traveled = 25s/26.4 meter
thus, the remaining distance Anneke need to travel is:
m = 500 - (25s/26.4)