What you’ll learn
Interpret expressions in context.
Key idea
Unit price times count is variable cost; the constant remains when no items are used.
Rate times count is variable cost; zero-use output identifies the fixed amount with dollar units.
Worked example
Classify examples and non-examples for the concept 'Interpret expressions in context'.
Supplied rental plan C=10+9n dollars for n rentals. Interpret the term 9n in this context.
- The fixed 10-dollar term is independent of n rentals; 9 dollars/rental×n rentals gives 9n dollars.
- Table n: 0,1,2; C: 10,19,28 shows the fixed zero-use fee and constant 9-dollar increment per rental.
Answer: 9n is variable rental cost — 9 dollars per rental times n rentals, separate from fixed 10 dollars.
Quick Check
Classify examples and non-examples for the concept 'Interpret expressions in context'.
Supplied rental plan C=30+2n dollars for n rentals. Interpret the term 2n in this context.