Your score would be 3. add -1, -4, and -8 together and get -13, then subtract 10 since 10 is positive and 13 is negative and get the answer 3. hope this made sense:)
125% as a fraction would be 125/100, which you can simplify to 5/4, or 1 1/4. 125% as a decimal would be 1.25, because you would do the sum 125 ÷ 100 = 1.25