Good morning people i hope you are having a great day um free points

This question awards 100 ! i really don’t want to fail i will also mark you !

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.

Amachine part consists of a half sphere and a cylinder, as shown in the figure. the total volume of the part is π cubic inches.