$\"\"$

The percent is 28, and the whole is 75.

Let n represent the part.

The percent proportion is $\"\"$ .

Apply cross product property of equality: $\"\"$ then $\"\"$ .

$\"\"$

$\"\"$ (Multiply: $\"\"$ ) $\"\"$

Apply division property of equality: Divide each side by 100.

$\"\"$

$\"\"$ (Cancel common terms)

$\"\"$ (Divide: $\"\"$ ) $\"\"$

21 is 28 $\"\"$ of 75.