Im having problems with finding the first term, I will be able to do the second part of the question easily, as its just the formula.In an arithmetic progression, the sum of the first ten terms is 50, and the fith term is three times the second term. Find:

i) The first term

ii) The sum of the first 20 terms

My text book hasnt got any examples of this sort of question in it, so Im unsure how to go about trying to complete it.

thanks