Two wastewater streams A and B, having an identical ultimate BOD are getting mixed to 
form the stream C. The temperature of the stream A is 20 °C and the temperature of the stream C is 10 °C. It is given that 
∙ The 5-day BOD of the stream A measured at 20 °C=50 mg/l 
∙ BOD rate constant (base 10) at 20 °C=0.115 per day 
∙ Temperature coefficient = 1.135 
The 5-day BOD (in mg/l, up to one decimal place) of the stream C, calculated at 10 °C, is ___________