What is the degree (or radian) measure of the acute angle formed by lines with slopes $3$ and $\frac14$?

1. $\tan\theta=\left|\dfrac{m_1-m_2}{1+m_1m_2}\right|=\left|\dfrac{3-\frac14}{1+\frac34}\right|=\dfrac{11/4}{7/4}=\dfrac{11}7$.
2. $\theta=\boxed{\arctan\dfrac{11}7}$.