The area of lake erie is about 7.1538 times 10 to the power of 8 square miles. the area of the indian ocean is about 9.3214 times 10 to the power of 7 square miles. approximately how many times larger is the area of lake erie than that of the indian ocean?

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.