Thank you for your answer Chet, this is how far I get
K1=λ1*A/d1=0.033A/0.1=0.33A
K2=λ2*A/d2=0.14A/0.1=1.4A
Q=0.33A(TL-TM)=1.4A(TM-TR)
Not sure if I'm supposed to do the rest or how I'm supposed to eliminate TM
1.4/0.33≈4.24
TL-TM=4.24(TM-TR)
... TM=(TL+4.24TR)/5.4
Then I'm pretty much stuck..