Answer: 4
The number line diagram is below.
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Step-by-step explanation:
The expression - 4 - (-8) is the same as -4 + 8 because the two negatives cancel each other out to form a positive. Subtracting a negative is the same as adding a positive.
We'll start at -4 on the number line. Then move 8 units to the right to arrive at 4 on the number line.
Ultimately -4 - (-8) = -4 + 8 = 4
Side note: -4 + 8 is the same as 8 + (-4) or 8 - 4