//Variable declaration:
QbyA = 70000.0                    //Total heat loss (Btu/h)
Q = 450.0                       //Heat loss (Btu/h.ft^2)

//Calculation:
A = QbyA/Q                        //Area available for heat transfer (ft^2)

//Result:
printf("The area available for heat transfer is : %.1f ft^2 .",A)