Will It Slide?

A box rests on a ramp only while static friction can hold it: $mg\sin\theta$ must not be more than $\mu_s mg\cos\theta$. The mass cancels:

$$\tan\theta \le \mu_s \quad \text{(stays at rest)}$$

$\tan\theta$ is rise over run.

The box stays while friction can match mg sin θ. tan θ = rise / run.