Carly and simon are renting formal clothes for a wedding. they found a rental company that charges a fixed fee of $90.00 and an additional fee of $21.00 per hour. which of the following linear equations shows an hourly rate of $21.00? a. y = $0.90x + $0.21 b. y = $90.00x + $21.00 c. y = $21.00x + $90.00 d. y = $0.21x + $0.90

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.