Final volume is 120 L
According to the dilution equation;
M1V1 = M2V2
Where, M1 is the molarity and V1 is the volume of the concentrated solution, while M2 and V2 are the molarity and volume of the diluted solution respectively.
In this case;
M1 = 12.0 M
V1 = 30 L
M2 = 3.0 M
V2 = ?
Therefore;
V2 = M1V1 ÷ M2
= (12 × 30) ÷ 3
= 120 L
Hence, the final volume will be 120 liters