I don't know the answer to this algebra question 8-(-10).

It is the end of the school term. Are you saying you don't know what happens when you subtract a negative number?

A double negative is the same thing as a positive. So if you subtract (-10) from 8 you end up with 18. Does that make sense?

You may see it like that. A negative sign means 'reverse order'.

On a number line, situate your 8.
Going right (increasing in the numbers or adding) is given by the '+' sign.

Now, in your expression, you have the first '-'. So, instead of going right, you go in the reverse direction, that is you go left.

But now, you have another '-' sign, so you change again direction, which means you now are turning right!

If this simple diagram can help...

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