maths
posted by DeGraft on .
The thirteenth term of an arithmetic progrssion os 27 and the seventh term is three timees the second term. tind the first term,common difference and the sum of the first ten terms

term(13) = a+12d
so a+12d = 27 (equation #1)
term(7) = 3term(2)
a+6d = 3(a+d)
a+6d = 3a + 3d
2a  3d = 0 (equation #2)
It is easy to solve these two equations, (see if you can get a=3, d=2)
then use your formula for the sum of 10 terms.