The eccentricity of the hyperbola $25 x^2-9 y^2=225$ is .......

If $P\left(x_1, y_1\right)$ is a point on the hyperbola $x^2-y^2=a^2$, then $S P$. S'P $=$ .............

If the lengths of the transverse axis and the latusrectum of a hyperbola are 6 and $\frac{8}{3}$ respectively, then the equation of the hyperbola is ............