Keep in mind the the word "percent" translates to "for each 100." 25% can be read as "25 for each 100," which has the fractional representation 
and the decimal representation 0.25. All of these representations are just different ways of writing the same value.
Note too that the fraction can be reduced to 
, so what the question is really asking is: 1/4 of what number is 9?
Well, if we know that 1/4 of the number is 9, we can easily find how large the whole number is by finding all 4/4 of it (the <em>whole</em> number)<em /><em />, or 4 x 9, which multiplies out to 36.
Note too that the fraction
Well, if we know that 1/4 of the number is 9, we can easily find how large the whole number is by finding all 4/4 of it (the <em>whole</em> number)<em /><em />, or 4 x 9, which multiplies out to 36.