Let $f$ be a function such that $3 f ( x ) + 2 f \left( \frac { m } { 19 x } \right) = 5 x , x \neq 0$ where $m = \sum _ { i = 1 } ^ { 9 } ( i ) ^ { 2 }$, then $f ( 5 ) - f ( 2 )$ is equal to
Let $f$ be a function such that $3 f ( x ) + 2 f \left( \frac { m } { 19 x } \right) = 5 x , x \neq 0$ where $m = \sum _ { i = 1 } ^ { 9 } ( i ) ^ { 2 }$, then $f ( 5 ) - f ( 2 )$ is equal to