Для сравнения дробей надо привести их к общему знаменателю.
3/8 и 1/6 --- общий знаменатель 24
9/24 и 4/24 ----- 9/24 > 4/24
3/8 > 1/6
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5/8 и 7/10 ---- общ. знам. = 40
25/40 и 28/40 ----- 25/40 < 28/40
5/8 < 7/10
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3/7 и 9/21 ---- общ.знам. = 21
9/21 = 9/21
3/7 = 9/21
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3/5 и 5/8 -----общ.знам. = 40
24/40 и 25/40 ----24/40 < 25/40
3/5 < 5/8
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7/12 и 11/18 ------общ.знам. = 36
21/36 и 22/36----21/36< 22/36
7/12 < 11/18
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10/21 и 9/14 ----общ.знам. = 42
20/42 и 27/42 ---- 20/42 < 27/42
10/21 < 9/14