(a)[4]
The initial three terms of an arithmetic progression are $25$, $4p - 1$ and $13 - p$, with $p$ as a constant. Determine the value of the tenth term of the progression.
(b)[4]
The first three terms of a geometric progression are $25$, $4q - 1$ and $13 - q$, where $q$ is a positive constant. Determine the sum to infinity of the progression.