A number when divided by 4 is reduced by 21 it self. Then the number is.

$\begin{array}{l}letthenumberbex\\ \frac{x}{4}=x-21\\ nowtaking\text{'}x\text{'}onRHSto\\ \frac{x}{4}-x=-21\\ \frac{(x-4x)}{4}=-21\\ taking4onLHStoRHS\\ -3x=-21\times 4\\ -3x=-84\\ x=\frac{84}{3}\\ X=28\end{array}$