Step-by-step explanation:
On the left: possible outcome has the value of 1 (1) = 
On the right: 1 possible outcome has the value of 1 (1)=
=> the probability of possible P(sum)= 2
=
*
=
On the left: possible outcome has the value of 1 = 
On the right: 1 possible outcome has the value of 2 =
On the left: possible outcome has the value of 2 = 
On the right: 1 possible outcome has the value of 1 =
=> the probability of possible P(sum)= 3
=
*
+
*
=
On the left: possible outcome has the value of 1 = 
On the right: 1 possible outcome has the value of 3 =
On the left: possible outcome has the value of 2 = 
On the right: 1 possible outcome has the value of 2=
=> the probability of possible P(sum)= 4
=
*
+
*
=
On the left: possible outcome has the value of 2 = 
On the right: 1 possible outcome has the value of 3 =
=> the probability of possible P(sum)= 5
=
*
=