Calculate the magnetic potential difference $V_\rm m$ for the following paths as shown by the solid lines.
Dotted lines are only for there for symmetry aspects!
The wires conduct the following currents:
$|I_1|=2 ~\rm A$
$|I_2|=5 ~\rm A$
$|I_3|=11 ~\rm A$
$|I_4|=7 ~\rm A$
Pay attention to the signs of the currents (given by the diagrams) and of the results!
Result
Based on the right-hand rule and the part of a full revolution the following results:
Task: $+I_1 - I_2 = -3 ~\rm A$
Task: $+{{1}\over{4}} I3 = 11/4 ~\rm A$ (it does not matter which way the path goes from the startpoint to the endpoint, as long as it has the same direction and number of revolutions)
Task: $-{{1}\over{4}} I1 = -0.5 ~\rm A$
Task: $+2 \cdot I_2 - 1 \cdot I_3 = -1 ~\rm A$