| 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 ) ) ) |