1. (130*109+170*109)-6000=(130+170)*109-6000=26700
1) 130+170=300.
2) 300*109=32700.
3) 32700-6000=26700.
2. 350*408*2-(168+156):2=285438
1) 168+156=324.
2) 350*408=142800.
3) 142800*2=285600.
4) 324:2=162.
5) 285600-162=285438.
3. 140*105-(96*90-36*90)=140*105-((96-36)*90)=9300
1) 96-36=60.
2) 60*90=5400.
3) 140*105=14700.
4) 14700-5400=9300.