Sally decides to buy quarts of ice cream at $5 each and boxes of pizza at $10 each for her softball team. Part 1) Write an algebraic expression that represents the total cost of the food if Sally buys x quarts of ice cream and y boxes of pizza.

Part 2) What is the total cost of Sally’s purchase if x=4 and y=5? Be sure to show your work.

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.