Answer:
Equals positive or negative. Because minus a positive equals plus a negative.
(+15) - (+20) = (+15) + (-20)
If you want to lear the rules, use a plus symbol between the parts of the operation.
(+) + (+) = +
(-) + (-) = -
(+) + (-) = - or +
Generally speaking, if just one number have a negative sign, the result can be both positive or negative.