This just means what you've been doing previously.
Just write 95 + a or something, I don't know.
Also, you might want to look at number 10 again and flip it around.
And try to use words like subtract instead of 'minus.' It's impossible to minus something in math terms, but it's possible to subtract something. It's just a vocabulary and English thing, but your teacher will love you forever if you say these things right.