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 = 3122 - 55 \times P`.
If cookies were sold on the market for $56, what is the quantity demanded?
Plug the price $56 into the demand function:
`Q_d = 3122 - 55 \times P = 3122 - 55 \times 56 = 42`.