What is the value of x in the rhombus?
side a (x+6)
side b 2x

X+6=2x
As, sides of the rhombus are equal
Therefore, 
2x-x= 6
x=6 unit

If we are trying to equalize the 2 expressions, by solving the system, X would equal 6, because X(6)+6=12, while X(6)×2=12 aswell.

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The answer is 25uthere is no v in the question