| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 3factsumint4.1 |  |-  ( ph -> B e. Fin ) | 
						
							| 2 |  | 3factsumint4.2 |  |-  ( ( ph /\ x e. A ) -> F e. CC ) | 
						
							| 3 |  | 3factsumint4.3 |  |-  ( ( ph /\ k e. B ) -> G e. CC ) | 
						
							| 4 |  | 3factsumint4.4 |  |-  ( ( ph /\ ( x e. A /\ k e. B ) ) -> H e. CC ) | 
						
							| 5 | 1 | adantr |  |-  ( ( ph /\ x e. A ) -> B e. Fin ) | 
						
							| 6 | 3 | adantlr |  |-  ( ( ( ph /\ x e. A ) /\ k e. B ) -> G e. CC ) | 
						
							| 7 |  | anass |  |-  ( ( ( ph /\ x e. A ) /\ k e. B ) <-> ( ph /\ ( x e. A /\ k e. B ) ) ) | 
						
							| 8 | 7 | bicomi |  |-  ( ( ph /\ ( x e. A /\ k e. B ) ) <-> ( ( ph /\ x e. A ) /\ k e. B ) ) | 
						
							| 9 | 8 | imbi1i |  |-  ( ( ( ph /\ ( x e. A /\ k e. B ) ) -> H e. CC ) <-> ( ( ( ph /\ x e. A ) /\ k e. B ) -> H e. CC ) ) | 
						
							| 10 | 4 9 | mpbi |  |-  ( ( ( ph /\ x e. A ) /\ k e. B ) -> H e. CC ) | 
						
							| 11 | 6 10 | mulcld |  |-  ( ( ( ph /\ x e. A ) /\ k e. B ) -> ( G x. H ) e. CC ) | 
						
							| 12 | 5 2 11 | fsummulc2 |  |-  ( ( ph /\ x e. A ) -> ( F x. sum_ k e. B ( G x. H ) ) = sum_ k e. B ( F x. ( G x. H ) ) ) | 
						
							| 13 | 12 | eqcomd |  |-  ( ( ph /\ x e. A ) -> sum_ k e. B ( F x. ( G x. H ) ) = ( F x. sum_ k e. B ( G x. H ) ) ) | 
						
							| 14 | 13 | itgeq2dv |  |-  ( ph -> S. A sum_ k e. B ( F x. ( G x. H ) ) _d x = S. A ( F x. sum_ k e. B ( G x. H ) ) _d x ) |