[tex] \frac{x}{y} = \frac{2}{5} [/tex]⇒[tex]x= \frac{2y}{5} [/tex]
[tex] \frac{2x+5y}{3x+8y} = \frac{2 \frac{2y}{5} +5y}{3 \frac{2y}{5} +8y} = \frac{y( \frac{4}{9} +5)}{y( \frac{9}{5}+8) } = \frac{ \frac{4}{9} +5}{ \frac{4}{9}+8 } = \frac{49}{9} : \frac{49}{5} = \frac{49}{9} * \frac{5}{49} = \frac{5}{9} [/tex]
