If a:b=5:9 and b:c=6:11; Then Find a:c

10:33
$latex \because a:c=\frac{a}{c}=\frac{a}{b}\times \frac{b}{c}&s=2$
$latex => \frac{5}{9}\times \frac{6}{11}=\frac{10}{33}&s=2$
$latex => \frac{a}{c}=\frac{10}{31}&s=2$
=> a:c=10:31
Hence option [B] is the right answer.