Is 13/10 irrational or rational

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

Find the constant of variation for the relation and use it to write an equation for the statement. then solve the equation.

What are the first 4 terms in the multiplication pattern given by the formula 2×4n