theorem extracted_formal_statement_215 (a : NNReal) (ha : ↑a > 0) (b : NNReal) (hb : ↑b < ⊤) (hm : 1 ≤ ↑a * ↑b)
  (h_original_goal : 1 ≤ ↑a * ↑b) : 1 ≤ ↑(a * b) := sorry

State before:
case intro.intro
a : NNReal
ha : ↑a > 0
b : NNReal
hb : ↑b < ⊤
hm : 1 ≤ ↑a * ↑b
⊢ 1 ≤ ↑a * ↑b

Tactic: rw [← NNReal.coe_mul]

State after:
[case intro.intro
 a : NNReal
 ha : ↑a > 0
 b : NNReal
 hb : ↑b < ⊤
 hm : 1 ≤ ↑a * ↑b
 ⊢ 1 ≤ ↑(a * b)]

Relevant lemmas:
NNReal.coe_mul : ∀ (r₁ r₂ : NNReal), ↑(r₁ * r₂) = ↑r₁ * ↑r₂