Question 889043
Midpoint: (64+72)/2 = 136/2 = 68


The midpoint of the temperature range is 68 degrees. 


t is some unknown temp. The difference between the unknown temp and the midpoint is 68-t and it's forced to be positive when we write |68-t|


Notice how 72 - 68 = 4 and 68 - 64 = 4


So the temps can't fluctuate more than 4 degrees, which means the final answer is <font color="red">|68 - t| < 4</font>