If a/7 = b/3 = c/5 then find ( (a + b + c)/(b + c ) ).

Given, \(\frac{a}{7}\) = \(\frac{b}{3}\) = \(\frac{c}{5}\)

Here we can directly conclude that 

a = 7, b = 3, c = 5, hence

⇒ (\(\frac{a + b + c}{b + c }\)) = (\(\frac{7 + 3 + 5}{ 3 + 5 }\)) = \(\frac{15}{8}\)