P(x) = 3(x^2 + 10x + 5) - 5(x - k) in the polynomial p(x) defined above, k is a constant. if p(x) is divisible by x, what is the value of k?

We have the following polynomial:
 P (x) = 3 (x ^ 2 + 10x + 5) - 5 (x - k)
 Let's rewrite the polynomial:
 P (x) = 3x ^ 2 + 30x + 15 - 5x + 5k
 P (x) = 3x ^ 2 + 25x + 15 + 5k
 For the polynomial to be divisible by x, then the constant term must be equal to zero:
 15 + 5k = 0
 Clearing k:
 5k = -15
 k = -15 / 5
 k = -3
 Answer: 
 the value of k is: 
 k = -3