A mathematical expression like
is pronounced one minus two. "Minus" here refers to the mathematical arithmetic operation of subtraction. The following expression
seems sometimes to be pronounced minus one minus two and other times as negative one minus two. The term in front of the first number does not refer to a mathematical operation but rather to a sign.
Are both correct or only one version? In short my question is: How is a negative number such as "-1" pronounced correctly in mathematics?