The perimeter of square jklm is 48 units. what is the value of x?

"units" is satisfactory for units of measurement if no more specific choice is made.  

We are told that the perimeter of this square is 48 units.  That would be equal to 4s units, where s is the length of any one side of this square.

Thus, 48 units = 4(s units), or 48 units = 4s.  Then the side of the square has length  s = 48 units / 4 = 12 units.

Check:  If the length of one side is 12 units, what is the perimeter?

  P = 4(12 units) = 48 units.   Correct!

No solution : there is no number of boxes that she bought

Skew lines(segments) are lines(segments) in 3 dimensions that do not intersect the given segment and are not parallel to it.  ae, bf, eg, and fh are your skew segments.  i hope that : )