1)(1 8/13 • 13/42 + 5 5/7 : 8/21) : (8 1/8 + 3 1/2) =
= ( 21/13 • 13/42 + 40/7 : 8/21) : (65/8 + 7/2) =
= (1/2 + 15) : (65/8 + 28/8) =
= (1/2 + 30/2) : 93/8 = 31/2 : 93/8 = (31•8)/(2•93) =
= 4/3 = 1 1/3
2)13/5:91/15=13/5*15/91=3/7;
3/7+11/14=6/14+11/14=17/14;
40/7-81/16=640/112-567/112=73/112;
112/73*73/112=1;
17/14-1=3/14.