(20-19 3/4)+(17 3/4-17)+(2 1/2-17/24)=2 19/24.
1) 20-19 3/4= 19 4/4 - 19 3/4= 1/4.
2) 17 3/4-17=3/4.
3)2 1/2 - 17/24= 2 12/24-17/24= 1 36/24-17/24=1 19/24.
4)1/4+3/4+1 19/24= 6/24+18/24+1 19/24=24/24+1 19/24=1+1 19/24=2 19/24.
ответ: 2 19/24
25 7/9-8 3/4-(13 5/12+2 11/18)=25 7/9-8 3/4-13 5/12-2 11/18=232/9-35/4-161/12-47/18=928/36-315/36-483/36-94/36=6/36=1/6
