You can use a ratio of those who preferred new ones to all of them like this- 18:30. Then, make another ratio with a variable as the number you need to find out and the one you're comparing to- x:300. Put those together like this- 18:30=x:300. Since 300 is 10 times 30, you can multiply by the same factor on the other end of the ratio.(18 times 10) If you do that, you get a whopping 180 scouts who prefer the new uniforms out of 300 total scouts.