Question Number 66356 by sandeepkeshari0797@gmail.com last updated on 13/Aug/19
Answered by $@ty@m123 last updated on 13/Aug/19
$${Let}\:{the}\:{number}=\mathrm{10}{x}+{y} \\ $$$${ATQ}, \\ $$$$\mathrm{9}\left(\mathrm{10}{x}+{y}\right)=\mathrm{2}\left(\mathrm{10}{y}+{x}\right) \\ $$$$\mathrm{90}{x}+\mathrm{9}{y}=\mathrm{20}{y}+\mathrm{2}{x} \\ $$$$\mathrm{88}{x}=\mathrm{11}{y} \\ $$$$\mathrm{8}{x}={y}\:...\left(\mathrm{1}\right) \\ $$$${Also}, \\ $$$${x}+{y}=\mathrm{9} \\ $$$$\Rightarrow{x}+\mathrm{8}{x}=\mathrm{9} \\ $$$$\Rightarrow\mathrm{9}{x}=\mathrm{9} \\ $$$$\Rightarrow{x}=\mathrm{1} \\ $$$$\Rightarrow{y}=\mathrm{8} \\ $$$$\Rightarrow{Req}.\:{number}=\mathrm{18} \\ $$