If 5 is subtracted from each observation, then the coefficient of variation is 10% and if 5 is added to each observation, then the coefficient of variation is 6%, then the coefficient of  variation of given observations is ______

$\begin{array}{l}\mathrm{y}=\mathrm{x}-5\hspace{0.25em} \hspace{0.25em} \hspace{0.25em}\hspace{0.25em}\overline{\mathrm{y}}=\overline{\mathrm{x}}-5\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} {\mathrm{s}}_{\mathrm{y}}={\mathrm{s}}_{\mathrm{x}}\\ \text{ C.V. }=\frac{\mathrm{s}}{\mathrm{x}}\times 100\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}10=\frac{\mathrm{s}}{\overline{\mathrm{x}}-5}\times 100\hspace{0.25em} \hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\left(1\right)\\ \mathrm{y}=\mathrm{x}+5\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} \overline{\mathrm{y}}=\overline{\mathrm{x}}+5\hspace{0.25em} \hspace{0.25em}\hspace{0.25em}\hspace{0.25em} {\mathrm{s}}_{\mathrm{y}}={\mathrm{s}}_{\mathrm{x}}\\ \text{ C.V. }=\frac{\mathrm{s}}{\mathrm{x}}\times 100\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} 6=\frac{\mathrm{s}}{\overline{\mathrm{x}}+5}\times 100\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} \left(2\right)\end{array}$
Divide equation (1) by (2),
$\frac{5}{3}=\frac{\overline{\mathrm{x}}+5}{\overline{\mathrm{x}}-5}5\overline{\mathrm{x}}-25=3\overline{\mathrm{x}}+15\therefore \overline{\mathrm{x}}=20$
From (1), 10 $=\frac{\mathrm{s}}{15}\times 100\therefore \mathrm{s}=1.5$
The coefficient of variation $\mathrm{V}=\frac{\mathrm{s}}{\overline{\mathrm{x}}}\times 100=\frac{1.5}{20}\times 100=7.5\mathrm{\%}$