Let's apply

1. given = 12 volts r = 3 ohm = ?

solution = v / r i = 12 volts / 300 i = 4a

2. Given I=2A R=7 Ohm E=?

Solution:

E= IR

E= 2a •7 ohm

E= 14V

3. Given I=4A E=36V R=?

Solution = R=V/I R=36V/4A R=9 Ohm

Explanation:

Hope it helped :)