Please help me very important question.

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

An angle that measures between 90 and 180° is called a(,

Seymour is twice as old as cassandra. if 16 is added to cassandra’s age and 16 is subtracted from seymour’s age, their ages become equal. what are their present ages? show !