## Example

The demand for cookies follows the equation: `Q_d = 10 - P`

If price is $3, the quantity demanded is `Q_d = 10 - 3 = 7` cookies.

### Question

The demand for cookies follows the equation: `Q_d = 1725 - 66 \times P`.

If cookies were sold on the market for $26, what is the quantity demanded?

Plug the price $26 into the demand function:

`Q_d = 1725 - 66 \times P = 1725 - 66 \times 26 = 9`.