Eric starts with 10 milligrams of a radioactive substance. the amount of the substance decreases by 12 each week for a number of weeks, w. he writes the expression 10(12)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)w to find the amount of radioactive substance remaining after w weeks. use the drop-down menus to explain what each part of eric's and andrea's expressions mean. clear check eric's expression: 10(12)w 12: w: 10: (12)w: andrea's expression: (1? 0.2)w w: 0.2: 1? 0.2: