Answer: -20 degrees in 8 hrs
Step-by-step explanation: If the temperature is 8 degrees, after 1 hr, it would be 4.5 degrees, after 2 hr, it would be 1.0 degrees, after 3 hr, it would be -2.5 degrees, after 4 hr, it would be - 6.0 degrees, after 5 hr, it would be -9.5 degrees, after 6 hr, it would be -13.0 degrees, after 7 hr, it would be -16.5 degrees and after 8 hr, it would be -20 degrees.
