If $\dfrac{a}{3} = \dfrac{b}{4} = \dfrac{c}{7}$, then $\dfrac{a + b + c}{c}$ = ?

1. $\dfrac{1}{2}$

2. $\dfrac{1}{7}$

3. 2

4. 7

Let, $\dfrac{a}{3} = \dfrac{b}{4} = \dfrac{c}{7} = k$

We can express,

a = 3k, b = 4k, c = 7k

Substituting values in $\dfrac{a + b + c}{c}$, we get :

$\Rightarrow \dfrac{3k + 4k + 7k}{7k} \\[1em] \Rightarrow \dfrac{14k}{7k} \\[1em] \Rightarrow 2.$

Hence, option 3 is the correct option.