If \(a\), \(b\), and \(c\) are positive numbers such that \(3a = 4b = 5c\), and if \(a + b = kc\), what is the value of \(k\)?
(A)\(\frac { 12 } { 35 } \) (B)\(\frac { 5 } { 7 } \) (C)\(\frac { 10 } { 7 } \) (D)\(\frac { 7 } { 5 } \) (E)\(\frac { 35 } { 12 } \)
E