If you remove 1 from 11 you get ten but however when you remove 1 from 9 you still get ten how can this be?

The first way is obvious, 11-1 = 10

Even you would understand that.

For the second bit where taking 1 from 9, to get 10, the only possible way to this is if the 1 was actually - 1 as:

9 - (-1) = 10

Two minus together make a plus.

I hope this has answered your query,

Have a great day

10

Step-by-step explanation:

[9-]-1