Answer
The Amplitude is $4$
The Period is $ \pi$
See graph below
Work Step by Step
For
$y=a\sin c(x−h) + k$ $y =a \cos c(x−h) + k$,
Amplitude: $|a|$, Period: $\frac{2\pi} {|c|}$,
Given $y = 4 \sin (-2x)$
The Amplitude is $|4| = 4$
The Period is $\frac{2\pi}{|-2|} = \pi$
The transformations are as follows
The blue graph represents the graph of $\sin x$
The red graph represents the graph of the given function that is reflected about the y-axis, compressed horizontally by a factor of 0.5 (calculated by $\frac{1}{c}$) and stretched vertically by a factor of $4$
See graph below.