The eighth term of an arithmetic series is twice the third term. The sum of the first eight terms are 39.Calculate the first term. Please help i've been stuck for hours on this question

Answer 1

In that case, you must have forgotten your Algebra I. Look at what you know:

a+7d = 2(a+2d)
8/2 (2a+7d) = 39

or, massaged a bit,

a = 3d
8a+28d = 39