Question

.....does anyone know the answer its not 9 units

Answer 1

The answer is 10 units

Answer 2

Hello.

The answer is 10 units.

You can find this out by subtracting the two. You cannot subtract a negative, so it goes like this.

9 - (-1) => 9 + 1

10 units is your answer.

Hope this was helpful, and have a good day!