Help me solve it step by step, thanks in advance

5. A uniform rod 4-kg in mass and 5-m in length is balanced on a triangular pivot that is 2-m from the left-end of the rod. Two masses are then hung on the rod: a 12-kg block that is on the left-end of the rod; and a 4- kg block that is on the right-end of the rod. Where should and additional 5-kg mass be placed to balance out the system as shown below? 5-m long rod; 4-kg in mass 2-m 3-m 12-kg 5-kg 4-kg X=