The square shown below has a perimeter of 6x -20 units. what is the value of x?

A square has 4 equal sides.  If the perimeter of this square is 6x-20 units, then the side length is 1/4 of that:
                        6x-20       6x     20
side length = =   -  =  3x/2 - 5
                          4            4       4

Unfortunately, there's not enough info given here to calculate x.  Again, please share the illustration of this square.  Probably the needed info is there.

Suredude why not right

Think of it as five or above give it a shove. change the 5 or above to the right to a zero and add one to the number on the left.