√70 is because . Choose the best response to fill in the blanks above.

A
Irrational ; because it's perfect square

B
Irrational ; because it's a non-perfect square

C
Rational; because it's a perfect square

D
Rational ; because it's a non-perfect square

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?