3целых1/3-(4целых 1/5х+х):5целых4/7=8/15

3  1/3-(4 1/5х+х):5 4/7=8/153  1/3-5 1/5х:5 4/7=8/15-26/5х:39/7=8/15-3 1/3-26/5х*7/39=8/15-3 5/15-2/5х*7/3=3/15-3-14/15х=-2 12/1514/15х=2 12/15х=2 12/15:14/15х=42/15:14/15х=42/15*15/14х=42/14х=3