Can someone plz help me

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?

Which expression is the factorization of x^2+10+21

Last week , donnell practiced the piano 3 hours longer than marcus . together, marcus and donnell practiced the piano 11 hours . for how many hours did each young man practiced the piano