Calculus integral evaluation using substitution I have to find this integral:

Evaluate the integral using an appropriate substitution $$\int\dfrac{8e^x+7e^{-x}}{8e^x-7e^{-x}}\mathrm dx.$$

I've tried my solution $\ln\Big[15\cdot \sinh(x) + \cosh(x)\Big]$, however, it is wrong.
What do I have to do?

Hint: The top is the derivative of the bottom. So let the bottom be $u$. 
