Rob and mike are on a club swimming team.
they are training for a statewide swimming meet that will be held in the end of summer. the table shows how many hours rob and mike spent at practice each week
practice time (in hours). | swimmer|weekly|monday-friday|
rob. | 35. | 25 mike. | 30. | 20 question: write a possible expression to show how many hours rob and mike spend at swim practice over a period of 10 weekends . include parentheses and brackets in your expression.

and you

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.