[tex] \frac{a}{8} = \frac{b}{3} [/tex]
[tex]3a = 8b[/tex]
[tex]a = \frac{8b}{3} [/tex]
[tex] \frac{a + b}{2a + 3b} = \frac{ \frac{8b}{3} + b}{2 \times \frac{8b}{3} + 3b} = \frac{ \frac{8b}{3} + \frac{3b}{3} }{ \frac{16b}{3} + 3b } = \frac{ \frac{11b}{3} }{ \frac{16b}{3} + \frac{9b}{3} } = \frac{ \frac{11b}{3} }{ \frac{25b}{3} } = \frac{11b}{25b} = \frac{11}{25} [/tex]