3 3/4 : 10 2/5 = 3 11/13 : х
15/4 : 52/5 = 50/13 : х
15/4 * х = 52/5 * 50/13 - свойство пропорции
15/4 * х = (4*10)/(1*1)
15/4 * х = 40
х = 40 : 15/4
х = 40 * 4/15
х = (8*4)/3
х = 32/3
х = 10 целых 2/3
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Проверка: 15/4 : 52/5 = 50/13 : 32/3
15/4 * 5/52 = 50/13 * 3/32
75/208 = 150/416 - верно (доп.множ.2)