| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mulgsubdi.b | ⊢ 𝐵  =  ( Base ‘ 𝐺 ) | 
						
							| 2 |  | mulgsubdi.t | ⊢  ·   =  ( .g ‘ 𝐺 ) | 
						
							| 3 |  | mulgsubdi.d | ⊢  −   =  ( -g ‘ 𝐺 ) | 
						
							| 4 |  | simpl | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝐺  ∈  Abel ) | 
						
							| 5 |  | simpr1 | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝑀  ∈  ℤ ) | 
						
							| 6 |  | simpr2 | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝑋  ∈  𝐵 ) | 
						
							| 7 |  | ablgrp | ⊢ ( 𝐺  ∈  Abel  →  𝐺  ∈  Grp ) | 
						
							| 8 | 7 | adantr | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝐺  ∈  Grp ) | 
						
							| 9 |  | simpr3 | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  𝑌  ∈  𝐵 ) | 
						
							| 10 |  | eqid | ⊢ ( invg ‘ 𝐺 )  =  ( invg ‘ 𝐺 ) | 
						
							| 11 | 1 10 | grpinvcl | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑌  ∈  𝐵 )  →  ( ( invg ‘ 𝐺 ) ‘ 𝑌 )  ∈  𝐵 ) | 
						
							| 12 | 8 9 11 | syl2anc | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( ( invg ‘ 𝐺 ) ‘ 𝑌 )  ∈  𝐵 ) | 
						
							| 13 |  | eqid | ⊢ ( +g ‘ 𝐺 )  =  ( +g ‘ 𝐺 ) | 
						
							| 14 | 1 2 13 | mulgdi | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  ( ( invg ‘ 𝐺 ) ‘ 𝑌 )  ∈  𝐵 ) )  →  ( 𝑀  ·  ( 𝑋 ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) )  =  ( ( 𝑀  ·  𝑋 ) ( +g ‘ 𝐺 ) ( 𝑀  ·  ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) ) ) | 
						
							| 15 | 4 5 6 12 14 | syl13anc | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑀  ·  ( 𝑋 ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) )  =  ( ( 𝑀  ·  𝑋 ) ( +g ‘ 𝐺 ) ( 𝑀  ·  ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) ) ) | 
						
							| 16 | 1 2 10 | mulginvcom | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑀  ∈  ℤ  ∧  𝑌  ∈  𝐵 )  →  ( 𝑀  ·  ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) )  =  ( ( invg ‘ 𝐺 ) ‘ ( 𝑀  ·  𝑌 ) ) ) | 
						
							| 17 | 8 5 9 16 | syl3anc | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑀  ·  ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) )  =  ( ( invg ‘ 𝐺 ) ‘ ( 𝑀  ·  𝑌 ) ) ) | 
						
							| 18 | 17 | oveq2d | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( ( 𝑀  ·  𝑋 ) ( +g ‘ 𝐺 ) ( 𝑀  ·  ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) )  =  ( ( 𝑀  ·  𝑋 ) ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ ( 𝑀  ·  𝑌 ) ) ) ) | 
						
							| 19 | 15 18 | eqtrd | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑀  ·  ( 𝑋 ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) )  =  ( ( 𝑀  ·  𝑋 ) ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ ( 𝑀  ·  𝑌 ) ) ) ) | 
						
							| 20 | 1 13 10 3 | grpsubval | ⊢ ( ( 𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 )  →  ( 𝑋  −  𝑌 )  =  ( 𝑋 ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) ) | 
						
							| 21 | 6 9 20 | syl2anc | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑋  −  𝑌 )  =  ( 𝑋 ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) ) | 
						
							| 22 | 21 | oveq2d | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑀  ·  ( 𝑋  −  𝑌 ) )  =  ( 𝑀  ·  ( 𝑋 ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ 𝑌 ) ) ) ) | 
						
							| 23 | 1 2 | mulgcl | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵 )  →  ( 𝑀  ·  𝑋 )  ∈  𝐵 ) | 
						
							| 24 | 8 5 6 23 | syl3anc | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑀  ·  𝑋 )  ∈  𝐵 ) | 
						
							| 25 | 1 2 | mulgcl | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑀  ∈  ℤ  ∧  𝑌  ∈  𝐵 )  →  ( 𝑀  ·  𝑌 )  ∈  𝐵 ) | 
						
							| 26 | 8 5 9 25 | syl3anc | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑀  ·  𝑌 )  ∈  𝐵 ) | 
						
							| 27 | 1 13 10 3 | grpsubval | ⊢ ( ( ( 𝑀  ·  𝑋 )  ∈  𝐵  ∧  ( 𝑀  ·  𝑌 )  ∈  𝐵 )  →  ( ( 𝑀  ·  𝑋 )  −  ( 𝑀  ·  𝑌 ) )  =  ( ( 𝑀  ·  𝑋 ) ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ ( 𝑀  ·  𝑌 ) ) ) ) | 
						
							| 28 | 24 26 27 | syl2anc | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( ( 𝑀  ·  𝑋 )  −  ( 𝑀  ·  𝑌 ) )  =  ( ( 𝑀  ·  𝑋 ) ( +g ‘ 𝐺 ) ( ( invg ‘ 𝐺 ) ‘ ( 𝑀  ·  𝑌 ) ) ) ) | 
						
							| 29 | 19 22 28 | 3eqtr4d | ⊢ ( ( 𝐺  ∈  Abel  ∧  ( 𝑀  ∈  ℤ  ∧  𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 ) )  →  ( 𝑀  ·  ( 𝑋  −  𝑌 ) )  =  ( ( 𝑀  ·  𝑋 )  −  ( 𝑀  ·  𝑌 ) ) ) |