Answer
$24^{\circ}$.
Work Step by Step
The angle of refraction can be found from the law of refraction, which is equation 11–20. The speeds of the incoming and outgoing sound waves can be found from the equation given in the problem.
$$\frac{sin\theta_2}{ sin\theta_1}=\frac{v_2}{v_1}=\frac{331+0.60T_2}{331+0.60T_1}$$
$$ sin\theta_2= sin25^{\circ}\frac{331+0.60(-15)}{331+0.60(15)}=0.4002$$
$$ \theta_2= sin25^{-1}0.4002\approx 24^{\circ}$$