Please show every step clearly! Also, The blue is the answers, I simply want to check…

Please show every step clearly! Also, The blue is the answers, I
simply want to check my process.
3. A steel tube (k = 15 W/mK) has an inner diameter of 40 mm and a wall thickness of 5 mm. The temperatures of the fluid inside the tube and the ambient air are 5°C and 20 °C respectively, while the corresponding convection coefficients are 300 W/m2K and 5 W/m²K. Determine: 11.52 W/m a. The heat gain per unit length (W/m) b. Repeat part (a) with 1 cm thick insulation (k = 0.02 W/mK) St A I w