25.6% of what # is 21.12

• katie6wpg: 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.
• calculista:

  Let

  x------> the number

  we know that

  [tex] 25.6 [/tex]% is equal to

  [tex] \frac{25.6}{100} =0.256 [/tex]

  By using proportion

  [tex] 21.12=x*0.256 [/tex]

  divide by [tex] 0.256 [/tex] both sides

  [tex] \frac{x}{0.256} *0.256=\frac{21.12}{0.256} \\ \\ x=82.5 [/tex]

  therefore

  the answer is

  [tex] 82.5 [/tex]