15 POINTS PLEASE HELP!

List the elements of the set in roster notation. (enter empty or ∅ for the empty set.) {x | x is a letter in the word hippopotamus}

Roger and natalie travel in similar cars. roger's car drives the two miles to school in 7.5 minutes. natalie drives the same distance in the opposite direction but in only 6.5 minutes. what is true of their velocities?

He ! a group of farmers planned to clean 80 acres of wheat per day to finish the work on schedule. right before the work started, they received a new piece of machinery that them clean 10 more acres per day than originally planned. as a result of increased productivity in the last day before the deadline they only had to clean 30 acres. how many acres of wheat did the group of farmers have to clean?