| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							rngsubdi.b | 
							⊢ 𝐵  =  ( Base ‘ 𝑅 )  | 
						
						
							| 2 | 
							
								
							 | 
							rngsubdi.t | 
							⊢  ·   =  ( .r ‘ 𝑅 )  | 
						
						
							| 3 | 
							
								
							 | 
							rngsubdi.m | 
							⊢  −   =  ( -g ‘ 𝑅 )  | 
						
						
							| 4 | 
							
								
							 | 
							rngsubdi.r | 
							⊢ ( 𝜑  →  𝑅  ∈  Rng )  | 
						
						
							| 5 | 
							
								
							 | 
							rngsubdi.x | 
							⊢ ( 𝜑  →  𝑋  ∈  𝐵 )  | 
						
						
							| 6 | 
							
								
							 | 
							rngsubdi.y | 
							⊢ ( 𝜑  →  𝑌  ∈  𝐵 )  | 
						
						
							| 7 | 
							
								
							 | 
							rngsubdi.z | 
							⊢ ( 𝜑  →  𝑍  ∈  𝐵 )  | 
						
						
							| 8 | 
							
								
							 | 
							eqid | 
							⊢ ( invg ‘ 𝑅 )  =  ( invg ‘ 𝑅 )  | 
						
						
							| 9 | 
							
								
							 | 
							rnggrp | 
							⊢ ( 𝑅  ∈  Rng  →  𝑅  ∈  Grp )  | 
						
						
							| 10 | 
							
								4 9
							 | 
							syl | 
							⊢ ( 𝜑  →  𝑅  ∈  Grp )  | 
						
						
							| 11 | 
							
								1 8 10 6
							 | 
							grpinvcld | 
							⊢ ( 𝜑  →  ( ( invg ‘ 𝑅 ) ‘ 𝑌 )  ∈  𝐵 )  | 
						
						
							| 12 | 
							
								
							 | 
							eqid | 
							⊢ ( +g ‘ 𝑅 )  =  ( +g ‘ 𝑅 )  | 
						
						
							| 13 | 
							
								1 12 2
							 | 
							rngdir | 
							⊢ ( ( 𝑅  ∈  Rng  ∧  ( 𝑋  ∈  𝐵  ∧  ( ( invg ‘ 𝑅 ) ‘ 𝑌 )  ∈  𝐵  ∧  𝑍  ∈  𝐵 ) )  →  ( ( 𝑋 ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ 𝑌 ) )  ·  𝑍 )  =  ( ( 𝑋  ·  𝑍 ) ( +g ‘ 𝑅 ) ( ( ( invg ‘ 𝑅 ) ‘ 𝑌 )  ·  𝑍 ) ) )  | 
						
						
							| 14 | 
							
								4 5 11 7 13
							 | 
							syl13anc | 
							⊢ ( 𝜑  →  ( ( 𝑋 ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ 𝑌 ) )  ·  𝑍 )  =  ( ( 𝑋  ·  𝑍 ) ( +g ‘ 𝑅 ) ( ( ( invg ‘ 𝑅 ) ‘ 𝑌 )  ·  𝑍 ) ) )  | 
						
						
							| 15 | 
							
								1 2 8 4 6 7
							 | 
							rngmneg1 | 
							⊢ ( 𝜑  →  ( ( ( invg ‘ 𝑅 ) ‘ 𝑌 )  ·  𝑍 )  =  ( ( invg ‘ 𝑅 ) ‘ ( 𝑌  ·  𝑍 ) ) )  | 
						
						
							| 16 | 
							
								15
							 | 
							oveq2d | 
							⊢ ( 𝜑  →  ( ( 𝑋  ·  𝑍 ) ( +g ‘ 𝑅 ) ( ( ( invg ‘ 𝑅 ) ‘ 𝑌 )  ·  𝑍 ) )  =  ( ( 𝑋  ·  𝑍 ) ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ ( 𝑌  ·  𝑍 ) ) ) )  | 
						
						
							| 17 | 
							
								14 16
							 | 
							eqtrd | 
							⊢ ( 𝜑  →  ( ( 𝑋 ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ 𝑌 ) )  ·  𝑍 )  =  ( ( 𝑋  ·  𝑍 ) ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ ( 𝑌  ·  𝑍 ) ) ) )  | 
						
						
							| 18 | 
							
								1 12 8 3
							 | 
							grpsubval | 
							⊢ ( ( 𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 )  →  ( 𝑋  −  𝑌 )  =  ( 𝑋 ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ 𝑌 ) ) )  | 
						
						
							| 19 | 
							
								5 6 18
							 | 
							syl2anc | 
							⊢ ( 𝜑  →  ( 𝑋  −  𝑌 )  =  ( 𝑋 ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ 𝑌 ) ) )  | 
						
						
							| 20 | 
							
								19
							 | 
							oveq1d | 
							⊢ ( 𝜑  →  ( ( 𝑋  −  𝑌 )  ·  𝑍 )  =  ( ( 𝑋 ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ 𝑌 ) )  ·  𝑍 ) )  | 
						
						
							| 21 | 
							
								1 2
							 | 
							rngcl | 
							⊢ ( ( 𝑅  ∈  Rng  ∧  𝑋  ∈  𝐵  ∧  𝑍  ∈  𝐵 )  →  ( 𝑋  ·  𝑍 )  ∈  𝐵 )  | 
						
						
							| 22 | 
							
								4 5 7 21
							 | 
							syl3anc | 
							⊢ ( 𝜑  →  ( 𝑋  ·  𝑍 )  ∈  𝐵 )  | 
						
						
							| 23 | 
							
								1 2
							 | 
							rngcl | 
							⊢ ( ( 𝑅  ∈  Rng  ∧  𝑌  ∈  𝐵  ∧  𝑍  ∈  𝐵 )  →  ( 𝑌  ·  𝑍 )  ∈  𝐵 )  | 
						
						
							| 24 | 
							
								4 6 7 23
							 | 
							syl3anc | 
							⊢ ( 𝜑  →  ( 𝑌  ·  𝑍 )  ∈  𝐵 )  | 
						
						
							| 25 | 
							
								1 12 8 3
							 | 
							grpsubval | 
							⊢ ( ( ( 𝑋  ·  𝑍 )  ∈  𝐵  ∧  ( 𝑌  ·  𝑍 )  ∈  𝐵 )  →  ( ( 𝑋  ·  𝑍 )  −  ( 𝑌  ·  𝑍 ) )  =  ( ( 𝑋  ·  𝑍 ) ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ ( 𝑌  ·  𝑍 ) ) ) )  | 
						
						
							| 26 | 
							
								22 24 25
							 | 
							syl2anc | 
							⊢ ( 𝜑  →  ( ( 𝑋  ·  𝑍 )  −  ( 𝑌  ·  𝑍 ) )  =  ( ( 𝑋  ·  𝑍 ) ( +g ‘ 𝑅 ) ( ( invg ‘ 𝑅 ) ‘ ( 𝑌  ·  𝑍 ) ) ) )  | 
						
						
							| 27 | 
							
								17 20 26
							 | 
							3eqtr4d | 
							⊢ ( 𝜑  →  ( ( 𝑋  −  𝑌 )  ·  𝑍 )  =  ( ( 𝑋  ·  𝑍 )  −  ( 𝑌  ·  𝑍 ) ) )  |