The ratio is 3 units to 5 units (3:5) We can subtract 3 from 5 to find out the difference between the Canadian stamps and American stamps is 2 units. The questions tells is this difference is 6 stamps, therefore 2 units = 6 stamps. Divide both sides by 2 to get 1 unit = 3 stamps. Lastly, multiply each side of the ratio by 3. 3x3= 9 Canadian stamps and 3x5= 15 American stamps.
15-9=6 so we know the answer is correct