Find the factors of c:
c = 90
Factors of 90: {1,2,3,5,6,9,10,15,18,30,45,90}
There is already a factor included in the factorization of this expression, which is 6. The factor that goes with 6 is 15.
Find the value of b by modifying the signs of the factors:
The missing factor is
B. z + 15.