Kirchhoff's Rules Were Applied to a Four-Loop Network $I_{1}, l_{2}, l_{3}$

Short Answer

Kirchhoff's rules were applied to a four-loop network. Solve for currents $I_{1}, l_{2}, l_{3}$ , and $I_{4}$ in this resulting system of equations:
$-6.0 I_{1}+2.0 I_{2}+4.0 I_{4}=-12$
$4.0 I_{1}+4.0 I_{2}-14 I_{4}=0$
$2.0 I_{1}-8.0 I_{2}+20 I_{3}+4.0 I_{4}=0$
$2.0 I_{2}-2.0 I_{3}=12$