a² - b² = (a - b)(a + b)

(a - b)² = a² - 2ab + b²

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(37² - 23²)/(83² + 23² - 23*166) = (37 - 23)(37 + 23)/(83² - 2*83*23 + 23²) = 14*60 / (83 - 23)² = 14*60 / 60² = 14/60 = 7/30