Microsoft® Visual Basic® Scripting Edition  Operator 
Language Reference

Used to find the difference between two numbers or to indicate the negative value of a numeric expression.
result = number1number2
numberThe  operator syntax has these parts:
Part Description result Any numeric variable. number Any numeric expression. number1 Any numeric expression. number2 Any numeric expression.
In Syntax 1, the  operator is the arithmetic subtraction operator used to find the difference between two numbers. In Syntax 2, the  operator is used as the unary negation operator to indicate the negative value of an expression.If one or both expressions are Null expressions, result is Null. If an expression is Empty, it is treated as if it were 0.