STATS MAKE ME CRY

Dear all, i desperately am looking for help, consider the following problem:

1. We have 1 set of data

Attribute Grouping Score

Age <=30 -5
<=60 0
>60

Weight <=100 -6
>100 10

Height <=100 -8
<=125 -5
<=150 -2
>150 1

and then we have the following score ranges

-19 to -5 A
-5 to 15 B
16 to 18 C

now say that someone who gets a score of say 1 (depending upon his attribute values) then he should have a result of (B)

my problem is that i need to scale here:

1. The values of column "Score" so that my over all score could be between 0 and 8 instead of (-19 to 18) and also based on the following ranges

0 to 3 = C
3 to 6 = B
6 to 9 = A

(please note we have also reversed the order)