If a: b=2: 5, then the value of (2 a+3 b):(7 a+ 5b) is · ABC26GN3006

$$\begin{aligned} & \frac{a}{b}=\frac{2}{5} \Rightarrow \frac{2 a+3 b}{7 a+5 b}=\frac{2\left(\frac{a}{b}\right)+3}{7\left(\frac{a}{b}\right)+5}=\frac{2 \times \frac{2}{5}+3}{7 \times \frac{2}{5}+5}=\frac{19}{5} \times \frac{5}{39}=\frac{19}{39} \\ & \Rightarrow(2 a+3 b):(7 a+5 b)=19: 39 \end{aligned}$$