What equation represents the slope intercept from the line below y intercept ( 0, 2) slope -3/7 ( PLEASE HELP FAST TOP ANSWER GETS BRAINLIEST!!)

I'm terrible at math any here is appreciated.

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?

To which sets of numbers does -12 belong? choose all answers that are correct. a) natural numbers b) integers c) real numbers d) irrational numbers