To solve this problem, we are going to use the percent proportion, a/b = p/100, where a is the part of a number b, the whole, and p is the percentage out of 100.
When we fill in our known integers into this equation, we get
21.12 / b = 25.6 / 100
Next, to simplify this equation, we should use cross products (means - extremes products theorem). This means multiplying the numerator of one fraction and the denominator of the other fraction and setting them equal to one another.
21.12(100)=25.6(b)
When we multiply, you get
2112 = 25.6b
Finally, we divide both sides by 25.6, to get our variable b, alone, and without a coefficient.
82.5 = b
Therefore, 25.6% of the number 82.5 is 21.12.