12 7/23-(6 18/23-t)=3 21/23+5 19/23
12 7/23 - (6 18/23 - t) = 3 21/23 + 5 19/23 12 7/23 - 6 18/23 + t = 3 21/23 + 5 19/23 t = 3 21/23 + 5 19/23 - 12 7/23 + 6 18/23 t = (3 +5 - 12 + 6) + (21/23 + 19/23 - 7/23 +18/23) = 6 + 51/23 = 6 + 2 5/23 = 8 5/23