98 17/87 - 2 25/29 -( 78 1/11 + 1 31/33 ×1,5 -78 20/21 ) : 2 1/21 =

1) 1 31/33 • 1,5 = 64/33 • 3/2 = 32/11 = 2 10/11
2) 78 1/11 + 2 10/11 = 80 11/11 = 81
3) 81 - 78 20/21 = 80 21/21 - 78 20/21 = 2 1/21
4) 2 1/21 : 2 1/21 = 1
5) 98 17/87 - 2 25/29 - 1 = 98 17/87 - 1 25/29 = 98 17/87 - 1 75/87 = 97 104/87 - 1 75/87 = 96 29/87 = 96 1/3
ответ 96 1/3