We can conclude the following information:
Every 3 hours the temperature changes.
<em>At 9 AM, the temperature </em><em><u>was -1.6°F</u></em><em>:</em>
9 AM = -1.6°F =>
<em>Between 9 AM and noon, the temperature </em><em><u>rose 6.6°F</u></em><em>:</em>
12 PM = -1.6 + 6.6 = 5°F =>
<em>Between noon and 3 PM, the temperature </em><em><u>increased by 2.8°F</u></em><em>:</em>
3 PM = 5 + 2.8 = 7.8°F =>
<em>Between 3 PM and 6 PM, the temperature </em><em><u>went down 10.5°F</u></em><em>:</em>
6 PM = 7.8 - 10.5 = -2.7°F
<em>What was the </em><em><u>temperature at 6 PM</u></em><em>? </em>
-2.7°F