(a)[3]
A geometric progression starts with term $100$ and has sum to infinity $2000$. Find the second term.
(b(i))[2]
An arithmetic progression has third term $90$ and fifth term $80$. Find the first term and the common difference.
(b(ii))[2]
Given that the sum of the first $m$ terms is equal to the sum of the first $(m + 1)$ terms, find the value of $m$.
(b(iii))[2]
Given that the sum of the first $n$ terms is zero, find the value of $n$.
(b)
The third term of an arithmetic progression is $90$ and the fifth term is $80$.