Show that the solution to the recurrence relation
$$T(n) = n \;\;\;\;\text{ for }\; n=1,2$$ $$T(n) = T(n/2) + T(n/3) + n \;\;\;\;\text{ for }\; n > 2$$
is $O(n)$ using substitution.
$$T(n) \leq c\cdot n - d$$ $$T(n) = \frac{c\cdot n}{2} - d + \frac{c\cdot n}{3} - d + n $$ $$T(n) = 5c\cdot n + 6n - 2d$$
I get stuck here. Any help is appreciated. Thanks in advance.