Реши устно и заполни пропуски

1. \(1250-90\implies\) [ ] \(+\,240\implies\) [ ] \(:40\implies\) [ ] \(+\,756\implies\) [ ].
2. \(600+1600\implies\) [ ] \(:110\implies\) [ ] \(+\,75\implies\) [ ] \(\cdot\,4\implies\) [ ].
3. \(1500:150\implies\) [ ] \(\cdot\,210\implies\) [ ] \(-\,450\implies\) [ ] \(+\,230\implies\) [ ].