Question 281029
They are all odd integers between 10 and 20
the odd integers between 10 and 20 are 11,13,15,17,19
take them in groups of three
which gives us three groups

11,13,15
13,15,17
15,17,19
 y and z are prime
but 15 is not prime so it can't be y nor z
which leaves only one group
so it must be 15, 17, 19
but the problem asks for x + y 
15+ 17=32
So the answer is 32