Magnetic deviation of a ship(aircraft) as a function of its heading is given by following equation
where delta = deviation, and the other greek letter is the ship's magentic heading.
But for our problem we don't have values of D & E, so we will just ignore the last two terms to have simple formula
DEV = A + B*sin(HDGm) + C*cos(HDGm)
deviation = -1 + -2*sin(295) -3*cos(295) = -0.5 degrees
Problem 2