Circle

$C_1$ is the circle with centre at $O(0,0)$ and radius $4, C_2$ is a variable circle with centre at $(\alpha, \beta)$ and radius 5 . If the common chord of $C_1$ and $C_2$ has slope $\frac{3}{4}$ and of maximum length, then one of the possible values of $\alpha+\beta$ is