Calculate the pay for the following day of a weekly time card given a wage of $15 an hour

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?

Could somebody me with this radical simplification?

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.