Heat transfer

PLEASE GIVE ME AN ANSWER WITH A DETAILED EXPLINATION, I REALLY NEED TO UNDERSTAND WHY

I just assumed the answer and got it right but I don't know why??? Could someone explain to me how to think with this picture and with others??

Ra RO T T10 T20 The heat flow (in [J/s]) through the wall of a tube of length L and inner radius Ro is Q = (27 ROL)U(T100 T200), where Tic. is the bulk temperature in the inside and T200 is the bulk temperature on the outside. The overall heat heat transfer coefficient reads as: 1 URO 1 hi Ro + In(Ra/Ro) k 1 + ha Ra (1) R R where Ro and Rq are the inner and outer radius of the tube, respectively, hi and h2 are the inner and outer heat transfer coefficients, and k is the thermal conductivity of the wall. How does Eq. (1) simplify for the T-profile shown on the left? O U = h1 Ro = + (6 1 hi 1 h2 U Ra 1 URO In(Ra/Ro) k 1 + haha OU U= k 1 Ro ln(Ra/Ro)