Steve rides his bike to and from work 5 days a week, 14 miles each way. Which of the following equations can be used to calculate the number of miles Steve commutes for work on his bike in x weeks? A.
y = 140x
B.
y = 70x
C.
y = 196x
D.
y = 14x

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.