А) х+1.75=3 2/3-1 1/2

х + 1,75 = 3²/₃ - 1½;

3²/₃ - 1½ = 3 ^{2 * 2}/_{3 * 2} - 1 ^{1 * 3}/_{2 * 3} = 3⁴/₆ - 1³/₆ = (3 - 1) + (⁴/₆ - ³/₆) = 2 + ¹/₆ = 2 ¹/₆;

1,75 = 1⁷⁵/₁₀₀ = 1 ^{75 : 25}/_{100 : 25} = 1 ¾;

х + 1³/₄ = 2¹/₆;

х = 2¹/₆ - 1¾;

2¹/₆ - 1¾ = 2 ^{1 * 2}/_{6 * 2} - 1 ^{3 * 3}/_{4 * 3} = 2²/₁₂ - 1⁹/₁₂ = 1 + ¹²/₁₂ + ²/₁₂ - 1⁹/₁₂ = 1¹⁴/₁₂ - 1^9/₁₂ =

= (1 - 1) + (¹⁴/₁₂ - ⁹/₁₂) = 0 + ⁵/₁₂ = ⁵/₁₂;

х = ⁵/₁₂.

Ответ: х = ⁵/₁₂.