HELP PLSSS THIS IS HARD SOMEONE

Y+ 2/y is it a polynomial in one variable or not? and if so, why?

Edith is shopping for a new leather couch. jordan’s furniture has one that costs $3,000. however, this weekend she can get a 15% discount. how much money will edith save if she buys the couch this weekend? a $15b $2,550c $45,000d $450

Walter is to make cookies for a basketball tournament. he's made 15 cookies so far. his coach asked him to make at least 20 cookies but no more than 55. solve the inequality and interpret the solution. 20 ? x + 15 ? 55