Researchers studied the relationship between how long a person uses a computer before bed and how long a person sleeps each night. People were selected at random to participate in the study. The computer use of each participant was classified as minimal, moderate, or extreme. The relative frequency table below summarizes the results of this study. There were 17 people in the study who were both moderate computer users and got 5 to 7 hours of sleep. How many people in this study were both extreme computer users and got 5 to 7 hours of sleep?

Celeste wants to have her hair cut and permed and also go to lunch. she knows she will need $50. the perm cost twice as much as her haircut and she needs $5 for lunch. how much does the perm cost?

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

How are algebraic expressions evaluated using substitution?