If the production function is characterized by constant returns to scale, what happens to real GDP (Y),

Question:

If the production function is characterized by constant returns to scale, what happens to real GDP (Y), capital per person (K/N), the ratio of output to capital (Y/K), and output per person (Y/N) when labor and capital inputs both double? What happens when labor and capital inputs double and the autonomous growth factor (A) also doubles?