Finding the Coefficient in a Polynomial

Let the polynomial function f(x) be defined as follows:

$$f(x) = 2x^4 - 3x^3 + ax^2 + bx + c$$

where a, b, and c are constants. When f(x) is divided by x - 2, the remainder is 5. When f(x) is divided by x + 1, the remainder is equal to the value of a at x = -1.

What is the value of a?