2) Electric heater wires are installed in a solid wall having a thickness of 8 cm and k=2.5 W/m.°C. The right face is exposed to an environment with h=50 W/m² °C and T-30°C, while the left face is exposed to h=75 W/m² °C and T-50°C. What is the maximum allowable heat generation rate such that the maximum temperature in the solid does not exceed 300°C?