Question

E= I(R+r) solve for r

Answer 1

I assume, since you did not give anything else but the formula, that you only need the formula to find r. The formula would be (E - IR)/I = r

Answer 2

`\sf (E - I R )/(I) =r`

Explanation:

E = I ( R + r )

Solve the brackets.

E = I R + I r

Subtract I R from both sides.

E - I R = I r

Divide both sides by r.

`\sf (E - I R )/(I) =r`