You've shown some work but you haven't really told us what the problem is that you are trying to solve and what Part A is and what Part B is.
It appears that your Part A is to find v(t) for t<0 and that your Part B is to find v(t) for t>0. Is that what you are thinking you are supposed to be doing?
If so, consider you proposed answer for Part A. What does your answer give for the value at -10 seconds?