411 REFERENCE · Wikibooks
PSLE Study Guide/Mathematics
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Sample question
80% of the fish in a tank were guppies and the rest were mollies. After 27 guppies and 12 mollies left the tank, 75% of the fish in the tank were guppies. Find the total number of fish in the tank at first.