how do I solve this problem?

D A: Calculate the Laplace transform of the following function: w(t) = cos (3t)u(t - 2) +e Stu(t - 5) Hint: cos (A + B) = cos(A) cos(B) - sin(A) sin(B) B: Use the Laplace transform to solve the IVP ODE: Ay" + 16y = e tu(t) , y (0) = 0, y' (0) = 0