A straight fin of rectangular profile is constructed of duralumin (94% Al, 3% Cu) with a thickness of 2.1 mm. The fin is 17 mm long, and it is subjected to a convection environment with h = 75 W/m2 ∙ ºC. If the base temperature is 100ºC and the environment is at 30ºC, calculate the heat transfer per unit length of fin.