Пошаговое объяснение:

(х + 5/12) - 9/20 = 11/15

х + 5/12 = 11/15 + 9/20

х + 25/60 = 44/60 + 27/60

х + 25/60 = 71/60

х = 71/60 - 25/60

х = 46/60

х = 23/30