Answer for our game

First section a+b=8 ; c-d=6

Second section a+c=13 ; b+d=8

Then we will first this (a+b=8) +(a+c=13) it comes =2a+b+c=21

Second we will add (c-d=6)+(b+d=8) it comes =c+b=14

Now to find A

we have 2a+b+c=21

therefore we know b+c=14

So, 2a+14=21

2A=21-14

2A=7

A=7/2 = 3.5

Now to find B

we have A=7/2

and in starting we know A+B=8

So, 7/2+B=8

B=8-7/2

B=9/2 =4.5

Now to find C

we have A=7/2

and in starting we know A+C=13

So, 7/2+C=13

C=13-7/2

C=19/2 = 9.5

Now to find D

we have B=9/2 and in starting we know B+D=8

So, 9/2+D=8

D=8-9/2

D=7/2 = 3.5

so we have the winners who will get 0.02 upvote

since no there is no 3rd participant i will give this two 0.03 upvote