Let
x-------> the length of the rectangle
y------> the width of the rectangle
we know that
the perimeter of a rectangle is equal to
[tex]P=2x+2y[/tex]
In this problem we have
[tex]x=8.3\ cm\\P=22.4\ cm[/tex]
substitute in the formula
[tex]22.4=2*8.3+2y[/tex]
Divide by [tex]2[/tex] both sides
[tex]11.2=8.3+y[/tex]
Solve for y
[tex]y=11.2-8.3[/tex]
[tex]y=2.9\ cm[/tex]
therefore
the answer is
[tex]2.9\ cm[/tex]
