[tex]v = \frac{er}{r + a} [/tex]
Find R in image
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Step-by-step explanation:
[tex]V = \frac{ER}{R + a} [/tex]
[tex]V(R+a)=ER[/tex]
[tex]VR + Va=ER[/tex]
[tex]Va= ER-VR[/tex]
[tex]Va=R(E-V)[/tex]
[tex]R = \frac{Va}{E-V} [/tex]