Question

A school’s math department has money to spend on calculators. It uses the equation y = 1,000 – 80x to determine how much money is left in the account to spend on calculators, where x represents the number of calculators purchased. What is the meaning of the slope of the equation?

A. Each calculator costs $1,000.


B. The account had $1,000 before buying calculators.


C. Each calculator costs $80.


D. The account had $80 before buying calculators.

Answer 1

C. Each calculator costs $80.

Explanation:

Linear equation:

Has the following format:

`y = mx + b`

In which m is the slope, and the meaning is how much the output changes when the input changes by 1 unit.

In this question:

Amount remaining after buying x calculators:

`y = 1000 - 80x`

So the slope of -80 means that each calculator costs $80, since after buying a calculator, 80 is retired from the amount.

The answer is given by option C.