ANSWER
The length of a side is
[tex]12 \: units[/tex]
EXPLANATION
The rhombus has all sides equal just like the square.
So [tex]|JK|=|JM|[/tex]
We can therefore write the following equation and use it to find x.
[tex]3x = 2x + 4[/tex]
We group like terms to get,
[tex]3x - 2x = 4[/tex]
This implies that,
[tex]x = 4[/tex]
We substitute the value of x in to the expression for one side to get,
[tex]JM=3 \times 4 = 12 \: \: units[/tex]
