(1 1/13+1 1/4)×1 19/56+2 5/8×1 3/7×1 1/9
11/13+11/4=3 31/52 3 31/52*1 19/56=4 2377/2912 2 5/8*1 3/7=3 3/4 3 3/4*11/9=4 7/12 4 2377/2912+4 7/12=9 3491/8736