Answer:
15c + 19d
Explanation:
Identify all like terms, or all terms with a c variable and all with a d variable.
3c, c, and 11c are your c's, and 14d and 5d are your d's.
Add the coefficients of each term (no coefficient means it's a 1!)
For the c's, 3+1+11 = 15 and for the d's, 14+5 = 19.
This gets you 15c + 19d. (They're already in alphabetical order, but if they weren't in a future problem, it would be good form to arrange them like that!)