One point is labeled "a" and two loops 1 and 2.
Using the point rule at a: I_{1} + I_{2} + I_{3} = 0
Using the loop rule in 1: 6 - 2I_{1} - 12(-I_{3}) = 0
Using the loop rule in 2: 8 + 12I_{3} = 0
Therefore I_{3} = 8/12 = 2/3 A
Subsitute in loop 1: 6 - 2I_{2} + (2/3)12 = 0
2I_{1} = 6 + 8 = 14
I_{1} = 7 A
From point rule: I_{2} = -I_{1} - I_{3} = -7 2/3 A