13 2/9-(7 5/9+у)=3 5 /9
-(7 5/9+y) = 3 5/9 -13 2/9 - 7 5/9 - y = -10 3/9 -y = - 10 3/9 + 7 5/9 -y = -3 8/9 y = 3 8/9