The last Harry Potter novel has just arrived and by 11 am a line has formed outside the crowded bookstore. Knowing you have class at noon, you ask the guard at the door how long you can expect to wait. She tells you that she is permitted to let 6 people into the store only after 6 people have left; customers are leaving at the rate of 2 customers per minute; and she has just let 6 new customers in. Also each customer spends an average of 15 minutes browsing at books and 10 minutes waiting in line to check out. How many minutes are there between groups of customers entering the book store?

Apublic library wants to place 4 magazines and 9 books on each display shelf. the expression 4s+9s represents the total number of items that will be displayed on s shelves. simplify the expression

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex

Desmond wants to sell his car that he paid $8,000 for 2 years ago. the car depreciated, or decreased in value, at a constant rate each month over a 2-year period. if x represents the monthly depreciation amount, which expression shows how much desmond can sell his car for today? 8,000 + 24x 8,000 - 24x 8,000 + 2x 8,000 - 2xdesmond wants to sell his car that he paid $8,000 for 2 years ago. the car depreciated, or decreased in value, at a constant rate each month over a 2-year period. if x represents the monthly depreciation amount, which expression shows how much desmond can sell his car for today? 8,000 + 24x 8,000 - 24x 8,000 + 2x 8,000 - 2x