Starting at noon, the temperature dropped steadily at a rate of 0.8 degrees Celsius every hour. For each of these situations, write and solve an equation and describe what your variable represents.
a. How many hours did it take for the temperature to decrease by 4.4 degrees Celsius?
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b. If the temperature after the 4.4 degree drop was -2.5 degrees Celsius, what was the temperature at noon?

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.