First option is correct i.e. [tex]v = \frac{D}{2z}[/tex] .
What is variable in an equation?
Variable is a symbol( usually a letter) standing in for an unknown numerical value in an equation.
How to solve an equation for the variable?
To solve or isolate a variable means to get the variable on one side of the equation by itself.
According to the given question
we have an equation
D = 2zv and to solve for variable v
For solving the above equation for the variable v, make the variable v on one side of the equation by itself.
⇒ [tex]\frac{D}{2z} = \frac{2zv}{2z}[/tex] ( dividing both the sides by 2z)
⇒ [tex]v = \frac{D}{2z}[/tex]
Hence, option first is correct.
Learn more about variable of an equation here:
https://brainly.com/question/23571367
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