Basically you are working on percentages.
Your entire group is 252 people
25/175 = 0.1428 OR ~14.28% like disc golf.
252*0.1428 = 36 people like disc golf.
of these 36 "players" or likers of disc golf, 5/12 of them have their own disc.
You can get the fraction 5/12 into decimal form (0.416 or 41.6%)
36*0.416 = 15 people have their own disc.
What you are doing is changing these fractions to percents and multiplying the percent to whatever group to see how many people in the group like this sport or have a disc.
Another way is to use equal fractions. If 25 / 175 like disc golf then x / 252 like disc golf. Multiply by 252 on both sides so x= (252*25) / 175. x=36. Likewise, 5 / 12 = x / 36 you can see the denominator 36 is 3*12, so you can say the numerator is 3*5, or 15. or multiply by 36 on both sides so (36*5)/12 = 15.
