I need 40 mins of Khan and I dont know answer plz help. :)

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?

Aflagpole broke in a storm. it was originally 8 1 81 feet tall. 2 8 28 feet are still sticking straight out of the ground, where it snapped, but the remaining piece has hinged over and touches the ground some distance away. how far away is the end of the pole from the base of the pole along the ground?

If np3 /nc2 = 6, find the value of n