How to substitute numerically evaluated value in explicit function

In the attached simple calculations, I am performing the explicit calculations to evaluate the Oxygen variable that is defined by an expression containing BODr variable. I added the symbolic equal sign after the definition of the BODr variable to substitute its evaluated value.

The question is how the variable BODr can be substituted as 7429 kg/day(numerically evaluated value) and not as the symbolically evaluated value. I am using MathCAD 14.