W a t e r e x c e s s = 0.6 W ( 1 − [ N a + ] o b s 140 ) {\displaystyle Water\ excess=0.6W\left(1-{\frac {[Na^{+}]obs}{140}}\right)}
![{\displaystyle Water\ excess=0.6W\left(1-{\frac {[Na^{+}]obs}{140}}\right)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/969e9a02a038c628c7dd96ec4eefabce6626f8cb)