Two pills a day for 30 days, what is it?

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

Tell whether the two rates form a proportion

Atruck can be rented from company a $50 a day plus $0.60 per mile. company b charges $20 a day plus $0.80 per mile to rent the same truck. find the number of miles in a day at which the rental costs for company a and company b are the same