Affected Quadratic Equations.

2. A laborer built $35$ rods of stone wall. If he had built $2$ rods less each day, it would have taken him $2$ days longer. How many rods did he build a day on the average?

3. A man bought flour for $$30$. Had he bought $1$ barrel more for the same sum, the flour would have cost him $$1$ less per barrel. How many barrels did he buy?

4. A man bought some knives for $$6$. Had he bought $2$ less for the same money, he would have paid $25$ cents more for each knife. How many knives did he buy?

5. What number exceeds its square root by $30$?

Let $x^2$ denote the number.