Answer:
90 stamps from Canada, 108 stamps from the United States, and 135 stamps from the Rest of the World
Step-by-step explanation:
Since this is a problem of proportion we can use the Rule of three to solve this. We do this by multiplying the diagonal available values and dividing by the third value in order to get the missing variable, which in this case would be the number of stamps in the other country. Like so...
1.5 <=====> 135 stamps
1.2 <=====> x stamps (United States)
(1.2 * 135) / 1.5 = 108 stamps (United States)
1.5 <=====> 135 stamps
1 <=====> x stamps (Canada)
(1 * 135) / 1.5 = 90 stamps (Canada)
Finally, we can see that Katie had 90 stamps from Canada, 108 stamps from the United States, and 135 stamps from the Rest of the World. All creating a ratio or 1:1.2:1.5
