If a:b=5:7, find (3a+5b):(5a-2b)

50:11
$latex \because \frac{a}{b}=\frac{5}{7}&S=2$
$latex \therefore \frac{\left ( 3a+5b \right )}{5a-2b}=\frac{3\left ( \frac{a}{b} \right )+5}{5\left ( \frac{a}{b} \right )-2}&S=2$
$latex =>\frac{3\times \frac{5}{7}+5}{5\times \frac{5}{7}-2}=\frac{50}{11}&S=2$
$latex =>a:b=50:11 $
Hence option [C] is the right answer.