A composite wall of area 2 m^{2} separates hot air at 100 °C (h = 10) from cold air at 20 °C (h = 25 W/m^{2}·K). Layers: brick 0.100 m, k = 0.72; insulation 0.050 m, k = 0.05; steel 0.005 m, k = 0.05 W/m·K. Find the heat transfer rate. (answer in W)