A bag contains red discs, white discs and blue discs. 1/6 of the discs are red, 1/4 of the discs are blue. What is the smallest possible number of white discs?

We are given the fractions representing the number of discs in the bag. When comparing fractions, we should first find a common denomenator for them. The smallest common denomenator for 6 and 4 is 12 (43=12; 62=12). When converting fractions, remember the rule "Whatever we do to the bottom, we must do to the top." This means that 1/6 = 2/12 and 1/4 = 3/12. Now we add these two fractions together to get 5/12. This means that out of 12 discs in the bag, 5 of them are red and blue. This would allow us to work out the white discs to be 12-5=7 discs.