Retrieve result when tables related by combination key (two columns)

I am a beginner. Power Bi Desktop free version. Creating table visualization.

I have following tables:

Table1: 

C1 , C2, C3       

1      2    a

1      3    g

2      2    c

2      3    h

Table2: 

C11, C22, C4    

1      2     91

1      2     45

1      3     73

2      2     12

2      3     87

2      3     21 

Need result as:

1     2    a    91+45

1     3    g    73

2     2    c     12

2     3    h     87+21

So far, I've created only result as: 

1     2         91+45

1     3        73

2     2         12

2     3         87+21

But I am having trouble to add values of C4 column values. 

My be to connect two tables on combination key that consists of 2 columns? Table1: C1,C2  and Table2: C11, C22 How to do that?  There is no many-to-many relationship in PBI.

Please help.

Many thanks