Mathematics

Problem

If the foci of the ellipse

\frac{x^2}{16} + \frac{y^2}{b^2} = 1

and the hyperbola

\frac{x^2}{144} - \frac{y^2}{81} = \frac{1}{25}

coincide, then the value of

b^2

is a. 1 b. 5 c. 7 d. 9