1 способ.
7 целых 1/4 - 3 целых 7/15 = (7-3)+(1/4-7/15)= 4 + (15/60 - 28/60) = 4 - 13/60 = 3 целых 60/60 - 13/60 = 3 целых 47/60;
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2 способ.
7 целых 1/4 - 3 целых 7/15 = 29/4 - 52/15 = 435/60 - 208/60 = 227/60 = 3 целых 47/60;