A Brass Rod Is Placed Between Two Temperature Sources So

A brass rod is placed between two temperature sources so that heat can flow between them. One temperature is 80 °C and the other temperature is 20 °C. The length of the rod is 50.0 cm and the cross-sectional area is 15.0 cm². If the thermal conductivity for brass is 100 W/m °C, then what is the heat flow between the hot temperature and the cold temperature?

A) 7.5 W
B) 8.2 W
C) 9.4 W
D) 12 W
E) 18 W