8.03x10^-8 MINUS 2.56x10^-2
To subtract these two numbers, you need to rewrite them in the same exponent form.
8.03x10^-8 = 0.0000000803
2.56x10^-2 = 0.0256
Now you can subtract them:
0.0000000803 - 0.0256 = -0.0255999197 (rounded to 10 decimal places)