ALGEBRAIC NOTATION.

4. If James is $x$ years old to-day, how old was he three years ago? How old will he be seven years hence?

5. Write four times the expression seven minus five. $4(7-5)$.

6. Write seven times the expression $2x$ minus $y$.

7. Write the next integral number above four. $4+1$.

8. If $x$ is an integral number, write the next integral number above it; the next integral number below it.

9. What number is less than $20$ by $d$?

10. If the difference of two numbers is five, and the smaller number is fifteen, what is the greater number? $15+5$.

11. If the difference of two numbers is eight, and the smaller number is $x$, what is the greater number?

12. If the sum of two numbers is $30$, and one of them is $20$, what is the other? $30-20$.

13. If the sum of two numbers is $x$, and one of them is $10$, what is the other?

14. If $100$ contains $x$ ten times, what is the value of $x$?

Exercise 7.

1. In $x$ years a man will be $40$ years old; what is his present age?

2. How old will a man be in $y$ years, if his present age is $a$ years?

3. What is the value of $x$ if $7x$ equals $28$?

4. If it takes $3$ men $4$ days to reap a field, how many days will it take one man to reap it? $3\times 4$.

5. If it takes $a$ men $b$ days to reap a field, how many days will it take one man to reap it?

6. What is the excess of $5x$ over $3x$?

7. By how much does $20-3$ exceed $(10+1)$? $20-3-(10+1)$.

8. By how much does $2x-3$ exceed $(x+1)$?

9. If $x$ stands for $10$, find the value of $4(3x-20)$.

10. If $a$ stands for $10$, and $b$ for $2$, find the value of $2(a-2b)$.

11. How many cents in $a$ dollars, $b$ quarters, and $c$ dimes?

12. A book-shelf contains French, Latin, and Greek books. There are $100$ books in all, and there are $x$ Latin and $y$ Greek books. How many French books are there?