Answer
$5$ inches
Work Step by Step
The original side is $ x $ inches (uknown).
The sides are now $(x+3)$ inches each, and
Area = $(x+3)^{2}$
$64=x^{2}+6x+9$
$0=x^{2}+6x-55$
Factor the RHS by finding factors of $-55$ with sum $+6$. We find $+11$ and $-5$
$0=(x+11)(x-5)$
$ w=-11$ is discarded as a negative side length, which makes no sense.
$ w=5 $ (inches) is the original side length.
