Answer:
1. So the porpotion should be 25/100 = x/120
You have this because you know that 25% of the dogs who go to ABC veterinarian need a rabies booster. So 100% of the dog should be 120 dogs, and now our job is to find how many dogs make up 25% percent of the total number.
According to our porpotion, we have:
(120 . 25)/100 = 30 (dogs)
Another way of understanding this is that you have to find 25% of the total amount, so just take that total number and multiply it with 25% or 25/100 which is 0.25 as well, that's why we multiply it with 25 first and then divide it to 100 later.
2.
*I guess there is no need of explaining it
0.9 × 550 = 495
