No! Remember, you see a negative exponent, that just means the reciprocal of the positive exponent. So 1 over negative 2 to the third power, to the positive third power. And this is equal to 1 over negative 2 times negative 2 times negative 2. ... So this is equal to negative 1/8.
You would do 20-(-25) which would make it 20+25 so the answer is 45 degrees