Sydney invests $70 every week into an account that pays 2.4% annual, compounded weekly. Benny invests $80 every month into an account that pays 2.2% annual interest rate, compounded monthly. Calculate the balance each person would have in their account after 10 years and 30 years.

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.