Let f be a function such that 3 f(x)+2 f(m/(19 x))=5 x, x ≠ 0, where m=Σ_i=1^9(i)^2. Then f(5)-f(2) is equal to

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