Find the Constant b in Function f(x)

Consider the function $$f(x) = 2x^3 - 3x^2 + ax + b$$, where $$a$$ and $$b$$ are constants. The function has a local maximum at $$x = 1$$ and a local minimum at $$x = 2$$. Find the value of $$b$$ given that the local maximum value at $$x = 1$$ is 4.