If $$a:3=b:7=c:9$$​, then $$\frac{a+b+c}{a}$$​ = ?

Correct option is C

​Given:

a : 3 = b : 7 = c : 9

Solution:

$$\frac{a}{3} = \frac{b}{7} = \frac{c}{9} = k \\ \ \\a = 3k,\quad b = 7k,\quad c = 9k \\ \ \\\frac{a + b + c}{a} = \frac{3k + 7k + 9k}{3k} = \frac{19k}{3k} = \frac{19}{3}$$​