RG = 2 + 1/(1/10 + 1/x) = 12 - 100/(x + 10)
IG = UG/RG = 22 / (12 - 100/(x + 10)) = 11·(x + 10)/((6·x + 10))
R1 * I1 = R2 * I2
I1 = I2 * R2 / R1 = 5 * x / 10
IG = I1 + I2
11·(x + 10)/((6·x + 10)) = 5 * x / 10 + 5
x = 2 und (x = -10)
U2 = R2 * I2 = 2 * 5 = 10 V