Delving deeper into the number line

Hello again.
I can hear your groans, but please, I'll try to make it as interesting as I can.
Here's a picture of a..... doughnut?

Feeling better?
How about another one?

I'm actually hungry now. I'm going to take one away.

What happened here? Save for your scowls and hurt, what I did, can be expressed in mathematical terms:
I added a negative doughnut to the two doughnuts.

I added the additive inverse of 1 to 2.
2+(-1)
Think of the negative doughnut as a creamy, strawberry doughnut, different from the chocolate oozing one, but just as yummy (yummier? i think so!)

Okay then.
Next, what if I were to take away a 'negative' doughnut from the two former chocolate doughnuts, magically replaced?

2-(-1)

I subtract the additive inverse from the two doughnuts.
Imagine extracting a pink doughnut from thin air, imagine dragging it across the number line, watching it magically turn warm and chocolatey.
Voila, you have three doughnuts with you? Happy now? You should be.

Do not get confused. I'm trying to 'foodie' up the number line is all!

Envisage this:
-3-(-4)

Let's talk more about the doughnut analogy.
Take -3 in the number line. You need to subtract -4 from it, or add 4 to it. Both are THE SAME.

You have 3 STRAWBERRY doughnuts with you. (-3 is what you start with)
You must take away 4 STRAWBERRY doughnuts.( you need to subtract -4)

Take one away, you have 2 strawberry doughnuts.
Take another away, you have 1.
Take another away, you have, *sad face* 0.

What happens after this? We have one more step left.
Now is the interesting bit.
Think of the balance doughnut being dragged right of 0 in the number line.
You have one chocolate doughnut.

Confused? Try re-reading it for a bit.
Try this:

-7-(-12)?

You end up with +5, or 5 chocolate doughnuts. Think about it, and try to solve it on your own.

Remember, in your coursework, please refer to our chocolate doughnuts as positives, and the strawberry ones as negatives. The teacher wouldn't understand otherwise!