#### Answer

The number is $360$.

#### Work Step by Step

step 1
Let x represent the unknown number in the problem.
step 2
"$ 70\%$ of a number" = $\displaystyle \frac{70}{100}\cdot x=0.7x$
" is $224$" is written as " = $252$"
step 3
The equation is
$0.7x=252$
step 4
Solve, answer the question.
$0.7x=252\qquad/\div 0.7$
$x=\displaystyle \frac{252}{0.7}=\frac{2520}{7}=360$
The number is $360$.
step 5
Check the solution in the original wording of the problem.
$7$0% of $360, \quad $($\displaystyle \frac{70}{100}\cdot 360=252),$
$...$ is $252$.
OK.