I tried setting up 4 equations using Kirchoffs laws, but the current source is throwing me off, as i dont know wether to include it in the loop, and if it would be smart to transform it into a voltage source.
The equations i have so far are:
I1 + I2 + I3 = I(R3)
I(R3) = I1 + I4
I4 = I2 + I3
U1 =...