WAEC 2024 · Paper 1 · Q34

The gradient of the line joining the points $P(2, -8)$ and $Q(1, y)$ is $-4$ . Find the value of $y$ .

Worked solution (try it first)

Gradient from $P$ to $Q$ : $\dfrac{y - (-8)}{1 - 2} = -4$ , so $\dfrac{y + 8}{-1} = -4$ .
Multiply both sides by $-1$ : $y + 8 = 4$ .
So $y = -4$ , option C.