XPRBvarSubtraction(Double, XPRBvar) Operator

public static XPRBexpr operator -(
	double d2,
	XPRBvar v1
)

Public Shared Operator - ( 
	d2 As Double,
	v1 As XPRBvar
) As XPRBexpr

XPRBvar var = new XPRBvar("Variable1");
XPRBexpr exp;
...
exp = 3.9-var;