| Step | Hyp | Ref
 | Expression | 
| 1 |   | elq 9696 | 
. 2
⊢ (𝐴 ∈ ℚ ↔
∃𝑥 ∈ ℤ
∃𝑦 ∈ ℕ
𝐴 = (𝑥 / 𝑦)) | 
| 2 |   | elq 9696 | 
. 2
⊢ (𝐵 ∈ ℚ ↔
∃𝑧 ∈ ℤ
∃𝑤 ∈ ℕ
𝐵 = (𝑧 / 𝑤)) | 
| 3 |   | nnz 9345 | 
. . . . . . . . . . . 12
⊢ (𝑤 ∈ ℕ → 𝑤 ∈
ℤ) | 
| 4 |   | zmulcl 9379 | 
. . . . . . . . . . . 12
⊢ ((𝑥 ∈ ℤ ∧ 𝑤 ∈ ℤ) → (𝑥 · 𝑤) ∈ ℤ) | 
| 5 | 3, 4 | sylan2 286 | 
. . . . . . . . . . 11
⊢ ((𝑥 ∈ ℤ ∧ 𝑤 ∈ ℕ) → (𝑥 · 𝑤) ∈ ℤ) | 
| 6 | 5 | ad2ant2rl 511 | 
. . . . . . . . . 10
⊢ (((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) → (𝑥 · 𝑤) ∈ ℤ) | 
| 7 |   | simpl 109 | 
. . . . . . . . . . 11
⊢ ((𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ) → 𝑧 ∈
ℤ) | 
| 8 |   | nnz 9345 | 
. . . . . . . . . . . 12
⊢ (𝑦 ∈ ℕ → 𝑦 ∈
ℤ) | 
| 9 | 8 | adantl 277 | 
. . . . . . . . . . 11
⊢ ((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) → 𝑦 ∈
ℤ) | 
| 10 |   | zmulcl 9379 | 
. . . . . . . . . . 11
⊢ ((𝑧 ∈ ℤ ∧ 𝑦 ∈ ℤ) → (𝑧 · 𝑦) ∈ ℤ) | 
| 11 | 7, 9, 10 | syl2anr 290 | 
. . . . . . . . . 10
⊢ (((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) → (𝑧 · 𝑦) ∈ ℤ) | 
| 12 | 6, 11 | zaddcld 9452 | 
. . . . . . . . 9
⊢ (((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) → ((𝑥 · 𝑤) + (𝑧 · 𝑦)) ∈ ℤ) | 
| 13 | 12 | adantr 276 | 
. . . . . . . 8
⊢ ((((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) ∧ (𝐴 = (𝑥 / 𝑦) ∧ 𝐵 = (𝑧 / 𝑤))) → ((𝑥 · 𝑤) + (𝑧 · 𝑦)) ∈ ℤ) | 
| 14 |   | nnmulcl 9011 | 
. . . . . . . . . 10
⊢ ((𝑦 ∈ ℕ ∧ 𝑤 ∈ ℕ) → (𝑦 · 𝑤) ∈ ℕ) | 
| 15 | 14 | ad2ant2l 508 | 
. . . . . . . . 9
⊢ (((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) → (𝑦 · 𝑤) ∈ ℕ) | 
| 16 | 15 | adantr 276 | 
. . . . . . . 8
⊢ ((((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) ∧ (𝐴 = (𝑥 / 𝑦) ∧ 𝐵 = (𝑧 / 𝑤))) → (𝑦 · 𝑤) ∈ ℕ) | 
| 17 |   | oveq12 5931 | 
. . . . . . . . 9
⊢ ((𝐴 = (𝑥 / 𝑦) ∧ 𝐵 = (𝑧 / 𝑤)) → (𝐴 + 𝐵) = ((𝑥 / 𝑦) + (𝑧 / 𝑤))) | 
| 18 |   | zcn 9331 | 
. . . . . . . . . . . 12
⊢ (𝑥 ∈ ℤ → 𝑥 ∈
ℂ) | 
| 19 |   | zcn 9331 | 
. . . . . . . . . . . 12
⊢ (𝑧 ∈ ℤ → 𝑧 ∈
ℂ) | 
| 20 | 18, 19 | anim12i 338 | 
. . . . . . . . . . 11
⊢ ((𝑥 ∈ ℤ ∧ 𝑧 ∈ ℤ) → (𝑥 ∈ ℂ ∧ 𝑧 ∈
ℂ)) | 
| 21 |   | nncn 8998 | 
. . . . . . . . . . . . 13
⊢ (𝑦 ∈ ℕ → 𝑦 ∈
ℂ) | 
| 22 |   | nnap0 9019 | 
. . . . . . . . . . . . 13
⊢ (𝑦 ∈ ℕ → 𝑦 # 0) | 
| 23 | 21, 22 | jca 306 | 
. . . . . . . . . . . 12
⊢ (𝑦 ∈ ℕ → (𝑦 ∈ ℂ ∧ 𝑦 # 0)) | 
| 24 |   | nncn 8998 | 
. . . . . . . . . . . . 13
⊢ (𝑤 ∈ ℕ → 𝑤 ∈
ℂ) | 
| 25 |   | nnap0 9019 | 
. . . . . . . . . . . . 13
⊢ (𝑤 ∈ ℕ → 𝑤 # 0) | 
| 26 | 24, 25 | jca 306 | 
. . . . . . . . . . . 12
⊢ (𝑤 ∈ ℕ → (𝑤 ∈ ℂ ∧ 𝑤 # 0)) | 
| 27 | 23, 26 | anim12i 338 | 
. . . . . . . . . . 11
⊢ ((𝑦 ∈ ℕ ∧ 𝑤 ∈ ℕ) → ((𝑦 ∈ ℂ ∧ 𝑦 # 0) ∧ (𝑤 ∈ ℂ ∧ 𝑤 # 0))) | 
| 28 |   | divadddivap 8754 | 
. . . . . . . . . . 11
⊢ (((𝑥 ∈ ℂ ∧ 𝑧 ∈ ℂ) ∧ ((𝑦 ∈ ℂ ∧ 𝑦 # 0) ∧ (𝑤 ∈ ℂ ∧ 𝑤 # 0))) → ((𝑥 / 𝑦) + (𝑧 / 𝑤)) = (((𝑥 · 𝑤) + (𝑧 · 𝑦)) / (𝑦 · 𝑤))) | 
| 29 | 20, 27, 28 | syl2an 289 | 
. . . . . . . . . 10
⊢ (((𝑥 ∈ ℤ ∧ 𝑧 ∈ ℤ) ∧ (𝑦 ∈ ℕ ∧ 𝑤 ∈ ℕ)) → ((𝑥 / 𝑦) + (𝑧 / 𝑤)) = (((𝑥 · 𝑤) + (𝑧 · 𝑦)) / (𝑦 · 𝑤))) | 
| 30 | 29 | an4s 588 | 
. . . . . . . . 9
⊢ (((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) → ((𝑥 / 𝑦) + (𝑧 / 𝑤)) = (((𝑥 · 𝑤) + (𝑧 · 𝑦)) / (𝑦 · 𝑤))) | 
| 31 | 17, 30 | sylan9eqr 2251 | 
. . . . . . . 8
⊢ ((((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) ∧ (𝐴 = (𝑥 / 𝑦) ∧ 𝐵 = (𝑧 / 𝑤))) → (𝐴 + 𝐵) = (((𝑥 · 𝑤) + (𝑧 · 𝑦)) / (𝑦 · 𝑤))) | 
| 32 |   | rspceov 5964 | 
. . . . . . . . 9
⊢ ((((𝑥 · 𝑤) + (𝑧 · 𝑦)) ∈ ℤ ∧ (𝑦 · 𝑤) ∈ ℕ ∧ (𝐴 + 𝐵) = (((𝑥 · 𝑤) + (𝑧 · 𝑦)) / (𝑦 · 𝑤))) → ∃𝑣 ∈ ℤ ∃𝑢 ∈ ℕ (𝐴 + 𝐵) = (𝑣 / 𝑢)) | 
| 33 |   | elq 9696 | 
. . . . . . . . 9
⊢ ((𝐴 + 𝐵) ∈ ℚ ↔ ∃𝑣 ∈ ℤ ∃𝑢 ∈ ℕ (𝐴 + 𝐵) = (𝑣 / 𝑢)) | 
| 34 | 32, 33 | sylibr 134 | 
. . . . . . . 8
⊢ ((((𝑥 · 𝑤) + (𝑧 · 𝑦)) ∈ ℤ ∧ (𝑦 · 𝑤) ∈ ℕ ∧ (𝐴 + 𝐵) = (((𝑥 · 𝑤) + (𝑧 · 𝑦)) / (𝑦 · 𝑤))) → (𝐴 + 𝐵) ∈ ℚ) | 
| 35 | 13, 16, 31, 34 | syl3anc 1249 | 
. . . . . . 7
⊢ ((((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ (𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ)) ∧ (𝐴 = (𝑥 / 𝑦) ∧ 𝐵 = (𝑧 / 𝑤))) → (𝐴 + 𝐵) ∈ ℚ) | 
| 36 | 35 | an4s 588 | 
. . . . . 6
⊢ ((((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) ∧ 𝐴 = (𝑥 / 𝑦)) ∧ ((𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ) ∧ 𝐵 = (𝑧 / 𝑤))) → (𝐴 + 𝐵) ∈ ℚ) | 
| 37 | 36 | exp43 372 | 
. . . . 5
⊢ ((𝑥 ∈ ℤ ∧ 𝑦 ∈ ℕ) → (𝐴 = (𝑥 / 𝑦) → ((𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ) → (𝐵 = (𝑧 / 𝑤) → (𝐴 + 𝐵) ∈ ℚ)))) | 
| 38 | 37 | rexlimivv 2620 | 
. . . 4
⊢
(∃𝑥 ∈
ℤ ∃𝑦 ∈
ℕ 𝐴 = (𝑥 / 𝑦) → ((𝑧 ∈ ℤ ∧ 𝑤 ∈ ℕ) → (𝐵 = (𝑧 / 𝑤) → (𝐴 + 𝐵) ∈ ℚ))) | 
| 39 | 38 | rexlimdvv 2621 | 
. . 3
⊢
(∃𝑥 ∈
ℤ ∃𝑦 ∈
ℕ 𝐴 = (𝑥 / 𝑦) → (∃𝑧 ∈ ℤ ∃𝑤 ∈ ℕ 𝐵 = (𝑧 / 𝑤) → (𝐴 + 𝐵) ∈ ℚ)) | 
| 40 | 39 | imp 124 | 
. 2
⊢
((∃𝑥 ∈
ℤ ∃𝑦 ∈
ℕ 𝐴 = (𝑥 / 𝑦) ∧ ∃𝑧 ∈ ℤ ∃𝑤 ∈ ℕ 𝐵 = (𝑧 / 𝑤)) → (𝐴 + 𝐵) ∈ ℚ) | 
| 41 | 1, 2, 40 | syl2anb 291 | 
1
⊢ ((𝐴 ∈ ℚ ∧ 𝐵 ∈ ℚ) → (𝐴 + 𝐵) ∈ ℚ) |