To find the factors, we must find all possible factors of c:
c = 24
Factors of 24: {1,2,3,4,6,8,12,24}
A set of these factors must add up to b. Add these factors together:
b = -10
1 + 24 = 25
2 + 12 = 14
3 + 8 = 11
4 + 6 = 10
-4 + -6 = 10
-4 and -6 will be used as the factors.
The answer is B. (x - 6y)(x - 4y).