Y denotes the quantity of output, L the quantity of labour, K the quantity of physical capital, H the quantity of human capital, and N the quantity of natural resources.
Constant returns to scale: a doubling of all the inputs causes the amount of output to double as well.
xY = A* F(x L, xK, xH, xN)
Set X = 1/L
Then Y/L = A* F( L/L, K/L, H/L, N/L)
= A* F( 1, K/L, H/L, N/L) where Y/L is output per worker, which is a measure of productivity. This equation says that productivity depends on physical capital per worker (K/L), human capital per worker (H/L) and natural resources per worker (N/L). Productivity also depends on the state of technology, A.