How to express subtraction in English?

Hello, I graduated from English Normal School. I hope I can help you.

Negative numbers in English can be used as long as they are negative. In the example, 5 1-28 can be said to be: fifty-one MINUS twenty-eight.

And the 1-8 added in your question can be translated as: one minus eight equals minus seven.

Did you get a look at him? Subtraction sign is used for negative sign in English, and only the concept of "negative, slightly lower" needs to be expressed by subtraction sign.