Which statement can be used to fill the blank space

Anyone know? will mark brainliest if correct!

The parabola y = x² - 4 opens: a.) up b.) down c.) right d.) left

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?