Question: cubic equations and odd percent signs

I have been searching for quite sometime, but I cannot find an answer to this.  So at last, I'm posting.

I keep trying to solve this equation below, and this is the outcome I get.  And, I have no idea what the solution means.  I am largely confused by the percentage signs, periods, etc...

Thanks in advance!

-kD

solve(((a-.5*b)*x^3 + (b-1.25*a)*x^2-1.5*a*x-c=0),x);
               1/3
0.1666666667 %2        0.1666666667 %3     0.1666666667 (-4. b + 5. a)
------------------ + ------------------- + ---------------------------,
   2. a - 1. b                       1/3           2. a - 1. b
                     (2. a - 1. b) %2

                      1/3
      0.08333333333 %2       0.08333333333 %3     0.1666666667 (-4. b + 5. a)
    - ------------------- - ------------------- + ---------------------------
          2. a - 1. b                       1/3           2. a - 1. b
                            (2. a - 1. b) %2

                      /               1/3                      \
                      |0.1666666667 %2        0.1666666667 %3  |
     + 0.8660254038 I |------------------ - -------------------|,
                      |   2. a - 1. b                       1/3|
                      \                     (2. a - 1. b) %2   /

                      1/3
      0.08333333333 %2       0.08333333333 %3     0.1666666667 (-4. b + 5. a)
    - ------------------- - ------------------- + ---------------------------
          2. a - 1. b                       1/3           2. a - 1. b
                            (2. a - 1. b) %2

                      /               1/3                      \
                      |0.1666666667 %2        0.1666666667 %3  |
     - 0.8660254038 I |------------------ - -------------------|
                      |   2. a - 1. b                       1/3|
                      \                     (2. a - 1. b) %2   /

              4          3            3           2  2          2  2
%1 := -3267. a  + 2376. a  b + 7980. a  c - 432. a  b  + 5184. a  c

               2                  2            2           3            2  2
     - 12024. a  c b + 5472. a c b  - 5184. a c  b - 768. b  c + 1296. c  b

              2             2         3           2                        2
%2 := -1002. a  b + 456. a b  + 665. a  + 864. c a  - 864. c a b + 216. c b

            3         1/2          1/2
     - 64. b  + 12. %1    a - 6. %1    b

           2                  2
%3 := 97. a  - 76. a b + 16. b