Writing Expressions
To write an expression, we often have to interpret a written phrase. For example, the phrase “ 6 added to some number” can be written as the expression x + 6, where the variable x represents the unknown number.
Some examples of common phrases and corresponding expressions that involve addition are:
Phrase |
Expression |
4 more than some number |
x + 4 |
a number increased by 10 |
y + 10 |
8 plus some number |
t + 8 |
the sum of a number and 12 |
w + 12 |
Some examples of common phrases and corresponding expressions that involve subtraction are:
Phrase |
Expression |
4 less than some number |
x – 4 |
a number decreased by 10 |
y – 10 |
8 minus some number |
8 – t |
the difference between a number and 12 |
w – 12 |
Some examples of common phrases and corresponding expressions that involve multiplication are:
Phrase |
Expression |
4 times some number |
4x |
twice a number |
2y |
one-third of some number |

|
the product of a number and 12 |
12w |
Some examples of common phrases and corresponding expressions that involve division are:
Phrase |
Expression |
the quotient of 4 and some number |
4x |
a number divided by 2 |

|
the ratio of 8 and some number |

|
the quotient of a number and 12 |

|
Some examples of common phrases and corresponding expressions that involve two operations are:
Phrase |
Expression |
6 more than 5 times a number |
5x + 6 |
4 times the sum of a number and 7 |
4(y + 7) |
5 less than the product of 3 and a number |
3w – 5 |
twice the difference between a number and 9 |
2(z – 9) |
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