find how many are not guppies now
99% of 200 are not guppies
100-99=1
1% of 200 is guppies
2 are guppies
now
2=2% of all
2=0.02 of all
divide both sides by 0.02
100=all
you need to have 100 left
you need to remove
200-?=100
-?=-100
?=100
you need to remove 100 non-guppy fish so that 2% of what remains is guppies
