(4) - (+8) = solve, how can this be an answer of negative?

The answer is -4 (negative four).

positive four minus positive eight = -4 because subtracting it downwards would be like 4 - 8 with your hands of where u say this, 3, 2, 1, 0, -1, -2, -3, and -4. 

And another reason its negative is because 4 is lower than 8 so if you're subtracting it that way than its negative, but if u do 8 - 4 than its positive.