We are given the dimensions of a rhombus. Thought it's not said, we'll assume the sides have the same length, so we can find the value of x, since no more conditions are provided
BC=4x-5
CD=2x+7
Since BC=CD
[tex]4x-5=2x+7[/tex]Adding 5
[tex]4x=2x+7+5=2x+12[/tex]subtracting 2x:
[tex]4x-2x=12\Rightarrow\text{ 2x=12}[/tex]Solving:
x=12/2=6
x=6
Option D. x=6