To find the factors, we must find all possible factors of c:
c = 77
Factors of 77: {1,7,11,77}
A set of factors must add up to b. Add these factors together:
b = 18
1 + 77 = 78
7 + 11 = 18
7 and 11 will be used in the factors.
The answer is A. (w + 7)(w + 11).