Question

Julie has 12 postcards from London. This is 30% of her collection. How many postcards does she have in her collection?

Answer 1

=> 30% means 0.30
=> "of"means "times"

So you can write        (0.30) times (collection)  =  12

Divide each side by 0.30 :                  Collection = (12) / (0.3)  =  40