Graphing Inquiry - Scaling function, then graphing it (and conserving units)

I want to scale M(x) equation by a scalar (0.805). Is there a way to do this without making my expressions unitless? After searching online for info about the error statement, I could not find a workaround.

Note: whenever 0.805 is not applied to M(x) the equation graphs properly. M(x) is defined in kip-ft.