It's all i the picture help!! i don't remember how to solve it

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?

What is the unit rate of, 75% high fiber chimp food to 25% high protein chimp food.

What number is 7 units left of -15?