To quantify the stoichiometric homeostasis index for N (nitrogen).

The formula is as follows:

log (y)= log(c) +(1/HP)log(x) (4)

where y is the N level in the plant tissue (mgkg−1), x is the N level in the water column (µgL−1), and c is a constant.

now my question id how to calculate the C or what is the value of C?