Answer:
The temperature six hours ago was 13 °F
Explanation:
Six hours ago the temperature was x degrees.
The temperature now is "6 degrees less than twice the temperature that it was six hours ago."
The temperature now is 2x - 6.
The temperature now is 20 deg.
2x - 6 = 20
2x = 26
x = 13
Answer: The temperature six hours ago was 13 °F.