How do I find the period of the sine function $y = 20\sin\left[\frac{5 \pi}{2}\left(\frac{x -2}{5}\right)\right] + 100$ Using Desmos I can see the period is $0.8$ but how do I get there?
I understand that the period is $2\pi/$co-efficient of $x$ but the $-2/5$ is throwing me off.

Shifts are to be neglected, hence, if $T$ is a period, we have
$$
\frac{5\pi}{2}T=2\pi,
$$
which gives $T=0.8$.
