[tex] \frac{a}{b} = \frac{3}{7} \\ \\ a= \frac{3b}{7} \\ \\ \frac{2a+b}{3a+2b}= \frac{2* \frac{3b}{7}+b }{ 3*\frac{3b}{7} +2b} = \frac{ \frac{6b}{7}+b }{ \frac{9b}{7}+2b } = \frac{ \frac{6b+7b}{7} }{ \frac{9b+14b}{7} } = \frac{13b}{7}: \frac{25b}{7} = \frac{13b}{7} * \frac{7}{23b} = \frac{13}{23} [/tex]
