i need solving this

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?

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.

Paul can type 60 words per minute and jennifer can type 80 words per minutes.how does paul's typing speed compare to jennifer's