#### Answer

$x=40$

#### Work Step by Step

Step 1. Let x represent one of the unknown quantities.
$x$ = the number
Step 2. Represent other unknown quantities in terms of x.
$0.30x$ = 30% of itself
Step 3. Write an equation in x that models the conditions.
$x-0.30x = 28$
Step 4. Solve the equation and answer the question.
$x-0.30x = 28$
$0.7x=28$
Divide both sides by 0.7:
$x=40$
Step 5. Check the proposed solution in the original wording of the problem.
if $x=40$
$x-0.30x = 28$
$40-0.30(40) = 28$
$40-12=28$
$28=28$-->TRUE