If 25, 35, $x$ are in proportion, find the value of $x$

The correct answer is 49

25, 35, $x$ are in proportion

⇒ 25, 35, 35, $x$ are in proportion

⇒ 25 : 35 :: 35 : $x$

⇒ $\dfrac{25}{35}$ = $\dfrac{35}{x}$

⇒ $x$ = $\dfrac{35 × 35}{25}$ = $49$

Hence $x$ = $49$