I have to find the laplace transform of the intrgral from 0 to (t-a) of f(u) du in terms of F(p) = laplace(f(t))

Do i use the convolution theorem where g(u) = 1

but even if i do that teh convolution theorem is the laplace of intregral from 0 to t of (f(t-u)g(u)) = F(p)G(p)

G(p) in our case would be 1/p?

but I dont know what to do with the (t-a)