At a florist's shop, two assistants made 13 flower arrangements in a certain amount of time. assuming all assistants will work for the same amount of time and each assistant is trained to work at the same rate, how many assistants are needed to make: 39 arrangements, 91 arrangements, and 195 arrangements.

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.