Theorem cnapbmcpd

Description: ((a+b)-c)+d = ((a+d)+b)-c holds for complex numbers a,b,c,d. (Contributed by Alexander van der Vekens, 23-Mar-2018)

	Ref	Expression
Assertion	cnapbmcpd	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → ( ( ( 𝐴 + 𝐵 ) − 𝐶 ) + 𝐷 ) = ( ( ( 𝐴 + 𝐷 ) + 𝐵 ) − 𝐶 ) )

Proof

Step	Hyp	Ref	Expression
1		addcl	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( 𝐴 + 𝐵 ) ∈ ℂ )
2	1	adantr	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → ( 𝐴 + 𝐵 ) ∈ ℂ )
3		simpr	⊢ ( ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) → 𝐷 ∈ ℂ )
4	3	adantl	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → 𝐷 ∈ ℂ )
5		simpl	⊢ ( ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) → 𝐶 ∈ ℂ )
6	5	adantl	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → 𝐶 ∈ ℂ )
7	2 4 6	addsubd	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → ( ( ( 𝐴 + 𝐵 ) + 𝐷 ) − 𝐶 ) = ( ( ( 𝐴 + 𝐵 ) − 𝐶 ) + 𝐷 ) )
8		simpl	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → 𝐴 ∈ ℂ )
9	8	adantr	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → 𝐴 ∈ ℂ )
10		simpr	⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → 𝐵 ∈ ℂ )
11	10	adantr	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → 𝐵 ∈ ℂ )
12	9 11 4	add32d	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → ( ( 𝐴 + 𝐵 ) + 𝐷 ) = ( ( 𝐴 + 𝐷 ) + 𝐵 ) )
13	12	oveq1d	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → ( ( ( 𝐴 + 𝐵 ) + 𝐷 ) − 𝐶 ) = ( ( ( 𝐴 + 𝐷 ) + 𝐵 ) − 𝐶 ) )
14	7 13	eqtr3d	⊢ ( ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) ∧ ( 𝐶 ∈ ℂ ∧ 𝐷 ∈ ℂ ) ) → ( ( ( 𝐴 + 𝐵 ) − 𝐶 ) + 𝐷 ) = ( ( ( 𝐴 + 𝐷 ) + 𝐵 ) − 𝐶 ) )