[tex]\displaystyle\bf\\3a-45=\frac{a}{2}\\\\3a-\frac{a}{2}=45\\\\\frac{6a-a}{2}=45\\\\\frac{5a}{2}=45\\\\5a=45\times2\\\\5a=90\\\\a=\frac{90}{5}\\\\\boxed{\bf~a=18}\\\\..................\\\\Incincitul~lui~a=5a\\\\Dublul~lui~a=2a\\\\5a-2a=3a\\\\3a=3\times18\\3a=3\times18\\3a=54\\\\\implies~\boxed{\bf~5a-2a=54}[/tex]
