JAMB Economics 2019 Paper

Concept:Substitute the given price into the demand equation to find the quantity consumers are willing to buy at that price.Explanation:The demand function is given as $Q_d = 80 - 2P$.Here, $P$ represents the price per unit, and $Q_d$ is the quantity demanded in units.The price given is $P = 3$ naira.To find the quantity demanded, replace $P$ with $3$ in the equation:$Q_d = 80 - 2(3)$.Multiply first: $2 \times 3 = 6$.Then subtract from $80$:$Q_d = 80 - 6$$Q_d = 74$.Answer:The quantity demanded is $74$ units when $P = ₦3$. Therefore, the correct option is C.