Let P(α, β) 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 (1, 5/4), then (α-28)(β-8) is…

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