7/20 * 15/17

16/15: 8/25

(3/4) в третьей степени * (4/3) в 3 степени

51/21: (8/25+9/20) - 64/35 * 5/4

(1/13+1/14) во 2 степени : (1/13 - 1/14) во 2 степени * (1/27) в 3 степени

1) 7/20*15/17 = 15/20*7/17 = 3/4*7/17 = 21/68

2) 16/15 : 8/25 = 16/15*25/8 = 16/8*25/15 = 2*5/3 = 10/3

3) (3/4) ^3 * (4/3) ^3 = (3/4*4/3) ^3 = 1^3 = 1

4) 51/21: (8/25+9/20) - 64/35*5/4 = 17/7: (32+45) / 100 - 64/4*5/35 =

= 17/7:77/100 - 16*1/7 = 17/7*100/77 - 16/7 = (1700 - 16*77) / (7*77) =

= (1700 - 1232) / 539 = 468/539

Наверное, тут какая-то опечатка, больно сложная дробь получилась.

5) (1/13+1/14) ^2 : (1/13-1/14) ^2 * (1/27) ^3 =

= (14+13) ^2 / (13*14) ^2 : (14-13) ^2 / (13*14) ^2 * 1/27^3 =

= 27^2 / (13*14) ^2 * (13*14) ^2/1 * 1/27^3 = 27^2/27^3 = 1/27