Metamath Proof Explorer

Theorem 7p7e14

Description: 7 + 7 = 14. (Contributed by Mario Carneiro, 19-Apr-2015)

Ref Expression
Assertion 7p7e14 
|- ( 7 + 7 ) = ; 1 4

Proof

Step Hyp Ref Expression
1 7nn0 
 |-  7 e. NN0
2 6nn0 
 |-  6 e. NN0
3 3nn0 
 |-  3 e. NN0
4 df-7 
 |-  7 = ( 6 + 1 )
5 df-4 
 |-  4 = ( 3 + 1 )
6 7p6e13 
 |-  ( 7 + 6 ) = ; 1 3
7 1 2 3 4 5 6 6p5lem 
 |-  ( 7 + 7 ) = ; 1 4