They are: 2+7+11 = 20
-20
3 + 17 = 20
3 and 17
600 * * * * * It is, in fact, 639
It is 1.
They are: 3+5+11 = 19
-20
148
It is 75.
17 and 3 are two prime numbers whose sum is 20. Their product is 51.
3 + 17 = 20
3 and 17
600 * * * * * It is, in fact, 639
17
It is 1.
(2,3) and (2,5) are the two pairs such that the sum of their elements is a prime number.
The three numbers will be 20, 22, and 24. 20 + 22 + 24 = 66