These problems are found in a calculus text at the end of a section on the 2nd FTC. I have examined these for a couple of hours, and cannot come to a solution.

Given: The indefinite integral[v(t-k)dt] = S(t) + C, where 'k' and 'C' are constants.

Find: S'(t)+c

Given: The indefinite integral[a*f(x)dx] = g(ax) + C, where 'C' is a constant and 'a' is a constant <>0.

Find: g'(x)