1) 2⁵/₇ - 1³/₅ = ¹⁹/₇ - ⁸/₅ = ¹⁹ˣ⁵/₃₅ - ⁸ˣ⁷/₃₅ = ⁹⁵⁻⁵⁶/₃₅ = ⁷⁷/₃₅
2) ³⁹/₃₅ : 1,3 = ³⁹/₃₅ : ¹³/₁₀ = ³⁹/₃₅× ¹⁰/₁₃ = ³⁹ˣ¹⁰/₃₅ₓ₁₃ = ⁶/₇
3) 1³/₇ × 0,25 = ¹⁰/₇ × ²⁵/₁₀₀ = ¹⁰ˣ²⁵/₇ₓ₁₀₀ = ¹⁰/₂₈ = ⁵/₁₄
4) ⁶/₇ - ⁵/₁₄ = ⁶ˣ²/₁₄ - ⁵/₁₄ = ¹²⁻⁵/₁₄ = ⁷/₁₄ = ¹/₂
5) ²/₅ - ⁷/₁₈ = ²ˣ¹⁸/₉₀ - ⁷ˣ⁵/₉₀ = ³⁶⁻³⁵/₉₀ = ¹/₉₀
6) ¹/₉₀ × 15 = ¹ˣ¹⁵/₉₀ = ¹⁵/₉₀ = ¹/₆
7) ¹/₂ : ¹/₆ = ¹/₂ × ⁶/₁ = ⁶/₂ = 3
Ответ: 3