Eric starts with 10 milligrams of a radioactive substance. The amount of the substance
decreases by each week for a number of weeks, w. He writes the expression
100)w to find the amount of radioactive substance remaining after w weeks.
Andrea starts with 1 milligram of a radioactive substance. The amount of the
substance decreases by 20% each week for a number of weeks, W. She writes the
expression (1 - 0.2)" to find the amount of radioactive substance remaining after w
weeks