Ответ:

1)5 7/9     2)5 1/6

Пошаговое объяснение:

1)18,75÷(4 1/3-2,25)-12 8/9÷4=5 7/9

1. 4 1/3-2,25=13/3-225/100=1300/300-675/300=625/300
2. 18,75÷625/300=1875/100×300/625=9
3. 12 8/9÷4=116/9×1/4=29/9
4. 9-29/9=81/9-29/9=52/9=5 7/9

2) (24 4/9÷8-15÷7,2)×7-1,25=5 1/6

1. 24 4/9÷8=216/9×1/8=27/9=3
2. 15÷7,2=15÷72/10=15×10/72=150/72
3. 3-150/72=216/72-150/72=66/72
4. 66/72×7=462/72
5. 462/72-1,25=462/72-125/100=23100/3600-4500/3600=18600/3600=93/18=31/6=5 1/6