(1 1/13+1 5/8)×(-1 11/ 1/12-1 5/8)×1 7/13

(1 1/13 + 1 5/8)*(-1 11/13)-(1 1/12 - 1 5/8)*1 7/13 = (14/13+13/8) * (-24/13) - (13/12-12/8) * 20/13 = (112+169)/104 * (-24/13) - (26-36)/24 * 20/13 = 281/104 * (-24/13) - (-10/24) * 20/13 = 281/26*6/13 + 10/6*5/13 = 1686/338 + 50/78 = (10116+1300)/2028 = 11416/2028 = 5 1276/2028 = 5 304/507 = 5,6