Answer:51 degrees
Step-by-step explanation:
At noon the temperature is 75 degrees
the temperature drops 3 degrees every half hour.
First solve for time elapsed between noon and 4, which is 4 hours.
Next, we can change our rate to be in terms of full hours instead of half hours using the fact that 1 hr = 2 half hours, so the temperature drops 6 degrees every hour.
Four hours have elapsed so multiply 6*4 = 24 degrees and then subtract it from the starting 75
75 - 24 = 51.
