MARKING BRAINLIEST
For what value of x is the rhombus below?

Answer:
x=2
Step-by-step explanation:
If this figure is a rhombus, then the two sides have to be equal:
3x+9=8x-1
Move like terms to one side (note that when you move it, the sign flips. Ex: - becomes +)
3x-8x=-9-1
-5x=-10
Divide both sides by -5
x=2