Answer:

Step-by-step explanation:

Double negative = Positive:

Apply negative exponent formula:

Multiply:

Apply exponent rule: 
Thus, 
Simplify:

The Greatest Common Factor of 55 and 80 is 5.
39. 13x3.....................
Answer:
Right
Step-by-step explanation:
Don't let fractions fool you.

of a tank in

an hour is equal to:
1/12 of a tank in 20 minutes.
Thus we know in an hour, an oil company can fill 3/12 of a tank (60 minutes in an hour).
3 x 4 = 12, and 12/12 = 1(a whole tank), so we multiply 1 (hour) by 4.
Our answer is that it takes 4 hours to fill a tank.