Subtracts the value of an expression from the value of a variable and assigns the result to the variable.
variable -= expression
The following example uses the -= operator to subtract one Integer variable from another and assign the result to the latter variable.
Dim var1 As Integer = 10
Dim var2 As Integer = 3
var1 -=
var2 ' The value of var1 is now 7.
&= Operator | *= Operator | += Operator | - Operator | /= Operator | = Operator | \= Operator | ^= Operator