Real analysis – Expected values ​​of handicaps.

The Gembling website offers those values ​​for a football game:

Bournemouth Draw Liverpool
6.50 4.50 1.47

The values ​​for ** 1: 0 handicap ** for the exact same match is:

Bournemouth Draw Liverpool
2.65 3.60 2.05

My question is how they extract the value of the handicaps from those values:

Bournemouth Draw Liverpool
6.50 4.50 1.47

Bournemouth to win (6.50) becomes Bournemouth 1: 0 Handicap to win (2.65)

[(HOME*DRAW)/(HOME+DRAW)]

so:

[(6.50*4.50)/(6.50+4.50)]    = ~ 2.65

But I do not understand how they reach the other values ​​of handicaps to draw and move away.

Just to clarify :

The 1: 0 disadvantage in the tie means that the away team MUST win in a 1 goal space.
So, for example, if the match ended in:

0: 1
1: 2
2. 3
3. 4
etc ...

all these cases win because it became a draw (because we added +1 to the draw), so:

0: 1 becomes -> 1: 1
1: 2 becomes -> 2: 2
2: 3 becomes -> 3: 3
3: 4 becomes -> 4: 4

What is the mathematical equation behind that?
(… my brain is on fire: P)