15 3/28 - (4 11/28+у)=7-1 9/28 15 3/28 - (4 11/28+у)=5 19/28 (4 11/28+у)=15 3/28-5 19/28 4 11/28+у=9 12/28 y=9 12/28- 4 11/28 y=5 1/28 15 3/28 - (4 11/28+5 1/28)=7-1 9/28 5 19/28=5 19/28