Writing the Nodal and Mesh equations for large circuit and large supermesh
For a supermesh enclosing both current sources you need to come up with three equations. One equation will be a KVL equation around a loop that encloses \$I_A\$ and \$I_B\$. I see only one loop that satisfies that requirement and has no current sources on the loop itself.

The second equation states the relationship between \$I_A\$, \$I_1\$, and \$I_3\$. The third equation similarly states the relationship between \$I_B\$ and mesh currents. These last two equations you should be able to write by inspection.