(1 1/7-2/5):(3/5+7/20)*1 6/13-3/26*5 1/5:3/5

(1 1/7 - 2/5) : (3/5 + 7/20) * 1 6/13 - 3/26 * 5 1/5 : 3/5 = 1/71) 1 1/7 - 2/5 = 1 5/35 - 14/35 = 40/35 - 14/35 = 26/352) 3/5 + 7/20 = 12/20 + 7/20 = 19/203) 26/35 : 19/20 = 26/35 * 20/19 = 104/1334) 104/133 * 1 6/13 = 104/133 * 19/13 = 8/7 = 1 1/75) 3/26 * 5 1/5 = 3/26 * 26/5 = 3/56) 3/5 : 3/5 = 17) 1 1/7 - 1 = 1/7

1 1/7 -2/5=8/7-2/5=40/35-14/35=26/353/5+7/20=12/20+7/20=19/2026/35÷19/20×1 6/13==26/35×20/19×19/13=8/7=1 1/73/26×5 1/5÷3/5=3/26×26/5×5/3=11 1/7-1=1/7