focus here don't solve all the problem I need just how to find the height of the fin

Exercise 1: Steam in a heating system flows through tubes whose outer diameter is D1 = 3 cm and whose walls are maintained at a temperature of 120. Circular aluminum fins (k = 180 WI m-C) of outer diameter D2 = 6 cm and constant thickness t = 2 mm are attached to the tube. The space between the fins is 3 mm, and thus there are 200 fins per meter length of the tube. Heat is transferred to the surrounding air at Tlo = 25C, with a combined heat transfer coefficient of h = 60 W/m2C. Determine the increase in heat transfer from the tube per r2 = 3 cm -1.5 cm meter of its length as a result of adding fins and the overall effectiveness. . h = 2 mm op S= 3 mm Afin A unfin A nofin = outer area of the pipe without fins