WHEN U ASK CALMY FOR AN ANSWER U DONT GET ONE, SO PLEASE HELP ME! I BEG OF U BRAINS! I am torn between the answers C and D. I have have heard of the vertical line test. But I don't know how to use it. If I could get the answers and an explanation it would help a ton :) (P. S There are multiple answers :) )

Someone me i need with this stuff

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.

If rs 900 amounts to rs 1044 in 4 years, what sum will amount to 1368 in 3 1/2 years at the same rate