Thermodynamics (Physics)

A Carnot engine (E) is working between two temperatures 473 K and 273 K. In a new system two engines - engine E1 works between 473 K to 373 K and engine E2 works between 373 K to 273 K. If 12, 1 and 2 are the efficiencies of the engines E, E1 and E2, respectively, then

1. 12 = 1 2
2. 12 = 1 + 2
3. 12 1 + 2
4. 12 < 1 + 2