If a, b, and c are prime numbers, do (a +

b. and c have a common factor that is greater than 1?

Let's do the math. In the example a = 2, b = 3, c = 5. If we are trying to see if the sum of these numbers has a common factor more than 1 do the math. 2 + 3 + 5 = 10. Ten has four factors which are 1, 2, 5, and 10. So the answer to your question is yes.