Исходные не пишу 538 2/9 и 1/3⇒2/9 и 3/9 13/15 и 7/10⇒26/30 и 21/30 5/12 и 3/5⇒25/60 и 36/60 539 2 5/9 и 3 3/7⇒2 35/63 и 3 27/63 1 2/3 и 1 7/15⇒1 10/15 и 1 7/15 1 7/9 и 2 7/12⇒1 28/36 и 2 21/36 544 7/10 и 2/9⇒63/90 и 20/90 2/3 и 3/10⇒20/30 и 9/30 1/2,4/5 и 3/4⇒10/20,16/20 и 15/20