Factory A pays its salesman 1 euro per item sold plus a fixed amount of 500 euros. Other factory B pays 1.5 euros per item and 300 euros fixed. How many items must the salesman from Factory B sell to earn more money than factory A? 6. What are the numbers whose square exceeds its own number by more than two?

7. A father and his son have been 30 years apart. Determine in what period of their lives the father's age exceeds by more than 10 years to twice the age of the child.