Ответ:
1. 7588
2. 99999
3. 9999 и 10001
4. 80000, 200, 10 и 5
5. 17100
6. 1420
7. 190
8. 1600
9. 3800
10. 700
7,2х+12y-4y= 7,2х+8y= 8(0,9х+y)=8*2=16