Writing Expressions

Expressions vs. Equations

Expressions use numbers, number symbols and letters (variables) to explain a sentence.

Equations are like expressions except they have an equal sign.

examples

twelve divided by three 12 ÷ 3

Twenty increased by eleven 20 + 11

Thirty-seven minus a number 37 - n

Real life problem

Joey mows lawns to make some extra money. He charges $21 for each lawn and an extra $2 per hour. Which expression should he use to find out how much to charge his customers?

[A] 21 + h

[B] 21 + 2·h

[C] 21 + 2

[D] 21 – 2·h

Translating words into symbols

Addition Subtraction Multiplication Division

Sum Difference Product Quotient

Increase Decrease Factors Equally shared

More than Less than Times Divided by

Plus Minus Multiplied by

Added to of

Example problems

Twelve pieces of candy equally shared by four friends 12 ÷ 4

The product of seven and four 7 x 4

The difference of Twenty and sixteen 20 – 16

y less than 18 times 6 18 • 6 – y

Example problems

1. Seven decreased by five7 – 5

2. The product of four and nine4 x 9

3. The sum of a number and tenm + 10

4. Eight more than a number c c + 8

Example problems5. The quotient of twenty and two

20 ÷ 2

6. Five minus a number x5 – x

7. Five less than a number x x – 5

8. Eighteen equally shared by six

18 ÷ 6

Example problems

9) Three times the sum of a number and 5 3 x (n + 5)

10) The quotient of m and 2 plus 7.

(m ÷ 2) + 7

four times the quantity of x minus 8 4 x (x – 8)

Eight more than the product of a number and 9 c + 8