Find the value of $x$ if 55:11 :: $x$:6

The correct answer is 30

As 55:11 :: $x$:6,
$\dfrac{55}{11}$ = $\dfrac{x}{6}$

⇒ $\dfrac{5}{1}$ = $\dfrac{x}{6}$

∴ $x$ = $\dfrac{5 × 6}{1}$ = 30

Hence $x$ = 30.