| Step | Hyp | Ref | Expression | 
						
							| 1 |  | modadd12d.1 | ⊢ ( 𝜑  →  𝐴  ∈  ℝ ) | 
						
							| 2 |  | modadd12d.2 | ⊢ ( 𝜑  →  𝐵  ∈  ℝ ) | 
						
							| 3 |  | modadd12d.3 | ⊢ ( 𝜑  →  𝐶  ∈  ℝ ) | 
						
							| 4 |  | modadd12d.4 | ⊢ ( 𝜑  →  𝐷  ∈  ℝ ) | 
						
							| 5 |  | modadd12d.5 | ⊢ ( 𝜑  →  𝐸  ∈  ℝ+ ) | 
						
							| 6 |  | modadd12d.6 | ⊢ ( 𝜑  →  ( 𝐴  mod  𝐸 )  =  ( 𝐵  mod  𝐸 ) ) | 
						
							| 7 |  | modadd12d.7 | ⊢ ( 𝜑  →  ( 𝐶  mod  𝐸 )  =  ( 𝐷  mod  𝐸 ) ) | 
						
							| 8 |  | modadd1 | ⊢ ( ( ( 𝐴  ∈  ℝ  ∧  𝐵  ∈  ℝ )  ∧  ( 𝐶  ∈  ℝ  ∧  𝐸  ∈  ℝ+ )  ∧  ( 𝐴  mod  𝐸 )  =  ( 𝐵  mod  𝐸 ) )  →  ( ( 𝐴  +  𝐶 )  mod  𝐸 )  =  ( ( 𝐵  +  𝐶 )  mod  𝐸 ) ) | 
						
							| 9 | 1 2 3 5 6 8 | syl221anc | ⊢ ( 𝜑  →  ( ( 𝐴  +  𝐶 )  mod  𝐸 )  =  ( ( 𝐵  +  𝐶 )  mod  𝐸 ) ) | 
						
							| 10 | 2 | recnd | ⊢ ( 𝜑  →  𝐵  ∈  ℂ ) | 
						
							| 11 | 3 | recnd | ⊢ ( 𝜑  →  𝐶  ∈  ℂ ) | 
						
							| 12 | 10 11 | addcomd | ⊢ ( 𝜑  →  ( 𝐵  +  𝐶 )  =  ( 𝐶  +  𝐵 ) ) | 
						
							| 13 | 12 | oveq1d | ⊢ ( 𝜑  →  ( ( 𝐵  +  𝐶 )  mod  𝐸 )  =  ( ( 𝐶  +  𝐵 )  mod  𝐸 ) ) | 
						
							| 14 |  | modadd1 | ⊢ ( ( ( 𝐶  ∈  ℝ  ∧  𝐷  ∈  ℝ )  ∧  ( 𝐵  ∈  ℝ  ∧  𝐸  ∈  ℝ+ )  ∧  ( 𝐶  mod  𝐸 )  =  ( 𝐷  mod  𝐸 ) )  →  ( ( 𝐶  +  𝐵 )  mod  𝐸 )  =  ( ( 𝐷  +  𝐵 )  mod  𝐸 ) ) | 
						
							| 15 | 3 4 2 5 7 14 | syl221anc | ⊢ ( 𝜑  →  ( ( 𝐶  +  𝐵 )  mod  𝐸 )  =  ( ( 𝐷  +  𝐵 )  mod  𝐸 ) ) | 
						
							| 16 | 4 | recnd | ⊢ ( 𝜑  →  𝐷  ∈  ℂ ) | 
						
							| 17 | 16 10 | addcomd | ⊢ ( 𝜑  →  ( 𝐷  +  𝐵 )  =  ( 𝐵  +  𝐷 ) ) | 
						
							| 18 | 17 | oveq1d | ⊢ ( 𝜑  →  ( ( 𝐷  +  𝐵 )  mod  𝐸 )  =  ( ( 𝐵  +  𝐷 )  mod  𝐸 ) ) | 
						
							| 19 | 13 15 18 | 3eqtrd | ⊢ ( 𝜑  →  ( ( 𝐵  +  𝐶 )  mod  𝐸 )  =  ( ( 𝐵  +  𝐷 )  mod  𝐸 ) ) | 
						
							| 20 | 9 19 | eqtrd | ⊢ ( 𝜑  →  ( ( 𝐴  +  𝐶 )  mod  𝐸 )  =  ( ( 𝐵  +  𝐷 )  mod  𝐸 ) ) |