Shell commands

Hey,

I have two seperate files with a column og data about item 277 and 289 in each. Fx:
277
-1.34534
-0.98272
0.12293
etc

and

289
-4.58493
9.88273
9.33829
etc.

How do i get the second input for item 277 (i.e. -.098272) and add or subtract it from the similar second input from the list for item 289

> cat file08
10
11
12
13
> cat file09
21
22
23
24
> paste file08 file09 | awk 'sumv=$1+$2 {print sumv}'
31
33
35
37
>

thanks for the help!