Answer :
5, 11 and 2 are all prime numbers which add together to create 18.
5+11=16+2=18
5+11=16+2=18
For these types of questions you have to think it out. List the prime source lower than 18. 2,3,5,7,11,13,17. Then take a look and test some pairs.
Eventually you'll find that 11, 5, 2 is a solution.
Eventually you'll find that 11, 5, 2 is a solution.