Question

25.6% of what # is 21.12

Answer 1

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.

Answer 2

Let

x------> the number

we know that

$25.6$% is equal to

$\frac{25.6}{100} =0.256$

By using proportion

$21.12=x*0.256$

divide by $0.256$ both sides

$\frac{x}{0.256} *0.256=\frac{21.12}{0.256} \\ \\ x=82.5$

therefore

the answer is

$82.5$