#### Answer

$-2\sin 11.5^{o}\cdot\cos 36.5^{o}$

#### Work Step by Step

Sum-to-Product:
$\displaystyle \sin A+\sin B=2\sin(\frac{A+B}{2})\cos(\frac{A-B}{2})$
$\sin(-A)=-\sin A$
----------
$\displaystyle \frac{A+B}{2}=\frac{25^{o}+(-48)^{o}}{2}=-11.5^{o}$
$\displaystyle \frac{A-B}{2}=\frac{25^{o}-(-48)^{o}}{2}=36.5^{o}$
$\sin 25^{o}+\sin(-48^{o})=2\sin(-11.5^{o})\cdot\cos(36.5^{o})$
$=-2\sin 11.5^{o}\cdot\cos 36.5^{o}$