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