Coordinate Geometry: JEE Main 2024 Mathematics question

Let $P(\alpha, \beta)$ be a point on the parabola $y^2=4 x$. If $P$ also lies on the chord of the parabola $x^2=8 y$ whose mid point is $\left(1, \frac{5}{4}\right)$, then $(\alpha-28)(\beta-8)$ is equal to _________.