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 = 2101 - 64 \times P`.
If cookies were sold on the market for $32, what is the quantity demanded?
Plug the price $32 into the demand function: $$Q_d = 2101 - 64 \times P = 2101 - 64 \times 32 = 53$$