| Step | Hyp | Ref
| Expression |
| 1 | | an4 797 |
. . 3
   
Nn    1c

 Nn   
1c      
Nn    1c  Nn    1c    |
| 2 | | simpl 443 |
. . . . 5
     |
| 3 | 2 | a1i 10 |
. . . 4
  Nn Nn Nn       |
| 4 | | reeanv 2779 |
. . . . 5
 
Nn 
Nn     1c    1c  
Nn    1c  Nn    1c   |
| 5 | | addccom 4407 |
. . . . . . . . . 10
1c 
 1c |
| 6 | | peano2 4404 |
. . . . . . . . . 10
 Nn 
1c
Nn  |
| 7 | 5, 6 | syl5eqel 2437 |
. . . . . . . . 9
 Nn 1c  Nn  |
| 8 | | nncaddccl 4420 |
. . . . . . . . 9
  Nn 1c  Nn  1c   Nn  |
| 9 | 7, 8 | sylan2 460 |
. . . . . . . 8
  Nn Nn  1c   Nn  |
| 10 | 9 | adantl 452 |
. . . . . . 7
   Nn Nn Nn  Nn Nn   1c   Nn  |
| 11 | | addceq1 4384 |
. . . . . . . . . 10
   
1c
     
1c
   |
| 12 | | addceq1 4384 |
. . . . . . . . . 10
       1c     1c     
1c
 1c  |
| 13 | 11, 12 | syl 15 |
. . . . . . . . 9
   
1c
 
 1c     
1c
 1c  |
| 14 | 13 | eqeq2d 2364 |
. . . . . . . 8
   
1c

   1c
     1c  1c   |
| 15 | 14 | biimpa 470 |
. . . . . . 7
     1c    1c      1c  1c  |
| 16 | | addceq2 4385 |
. . . . . . . . . . . 12
  1c   

  1c      |
| 17 | | addcass 4416 |
. . . . . . . . . . . . 13
    1c     1c    |
| 18 | | addcass 4416 |
. . . . . . . . . . . . 13
   1c     1c     |
| 19 | 17, 18 | eqtri 2373 |
. . . . . . . . . . . 12
    1c   
1c     |
| 20 | 16, 19 | syl6eqr 2403 |
. . . . . . . . . . 11
  1c   

  
 1c    |
| 21 | | addceq1 4384 |
. . . . . . . . . . 11
       1c     1c     
1c
 1c  |
| 22 | 20, 21 | syl 15 |
. . . . . . . . . 10
  1c      1c     
1c
 1c  |
| 23 | 22 | eqeq2d 2364 |
. . . . . . . . 9
  1c   
 
 1c     
1c
 1c   |
| 24 | 23 | rspcev 2956 |
. . . . . . . 8
   1c   Nn     
1c
 1c 
Nn    1c  |
| 25 | 24 | ex 423 |
. . . . . . 7
  1c  
Nn      
1c
 1c  Nn   
1c   |
| 26 | 10, 15, 25 | syl2im 34 |
. . . . . 6
   Nn Nn Nn  Nn Nn   
 
 1c    1c 
Nn    1c   |
| 27 | 26 | rexlimdvva 2746 |
. . . . 5
  Nn Nn Nn  
Nn 
Nn     1c    1c 
Nn    1c   |
| 28 | 4, 27 | syl5bir 209 |
. . . 4
  Nn Nn Nn   
Nn    1c  Nn    1c 
Nn    1c   |
| 29 | 3, 28 | anim12d 546 |
. . 3
  Nn Nn Nn      
Nn    1c  Nn    1c  

Nn    1c    |
| 30 | 1, 29 | syl5bi 208 |
. 2
  Nn Nn Nn    
Nn    1c

 Nn   
1c  

Nn    1c    |
| 31 | | opkltfing 4450 |
. . . 4
  Nn Nn     fin 
 Nn   
1c    |
| 32 | 31 | 3adant3 975 |
. . 3
  Nn Nn Nn     fin 
 Nn   
1c    |
| 33 | | opkltfing 4450 |
. . . 4
  Nn Nn     fin 
 Nn   
1c    |
| 34 | 33 | 3adant1 973 |
. . 3
  Nn Nn Nn     fin 
 Nn   
1c    |
| 35 | 32, 34 | anbi12d 691 |
. 2
  Nn Nn Nn      fin    fin  
 Nn   
1c 
 Nn   
1c     |
| 36 | | opkltfing 4450 |
. . 3
  Nn Nn     fin 
 Nn   
1c    |
| 37 | 36 | 3adant2 974 |
. 2
  Nn Nn Nn     fin 
 Nn   
1c    |
| 38 | 30, 35, 37 | 3imtr4d 259 |
1
  Nn Nn Nn      fin    fin    fin   |