Write variable expressions: word problems

Key notes:

A variable is a letter that represents an unknown number.

An expression is a group of numbers, symbols, and variables that represents another number.

Learn with an example

Vivian had 33 CDs until she won c more in a contest. Choose the expression that shows how many CDs Vivian has now.

  • c-33
  • 33-c
  • 33+c
  • c

Look for a pattern.

Try c = 2:

Vivian had 33 CDs until she won 2 more in a contest. Choose the expression that shows how many CDs Vivian has now.

33 + 2, which is 35

Try c = 3:

Vivian had 33 CDs until she won 3 more in a contest. Choose the expression that shows how many CDs Vivian has now.

33 + 3, which is 36

Try c = 4:

Vivian had 33 CDs until she won 4 more in a contest. Choose the expression that shows how many CDs Vivian has now.

33 + 4, which is 37

The pattern shows that in order to find how many CDs Vivian has now, you always add c to 33. This is the correct expression:

33 + c

Beth had d DVDs. Her mother bought her 91 more DVDs. Choose the expression that shows how many DVDs Beth has now.

  • d
  • 91-d
  • d+91
  • d-91

Look for a pattern.

Try d = 2:

Beth had 2 DVDs. Her mother bought her 91 more DVDs. Choose the expression that shows how many DVDs Beth has now.

2 + 91, which is 93

Try d = 3:

Beth had 3 DVDs. Her mother bought her 91 more DVDs. Choose the expression that shows how many DVDs Beth has now.

3 + 91, which is 94

Try d = 4:

Beth had 4 DVDs. Her mother bought her 91 more DVDs. Choose the expression that shows how many DVDs Beth has now.

4 + 91, which is 95

The pattern shows that in order to find how many DVDs Beth has now, you always add 91 to d. This is the correct expression:

d + 91

Kendra has 93 pieces of candy. She gives away c of the pieces. Choose the expression that shows the number of pieces of candy Kendra has left.

  • 93+c
  • c
  • c-93
  • 93-c

Look for a pattern.

Try c = 2:

Kendra has 93 pieces of candy. She gives away 2 of the pieces. Choose the expression that shows the number of pieces of candy Kendra has left.

93 − 2, which is 91

Try c = 3:

Kendra has 93 pieces of candy. She gives away 3 of the pieces. Choose the expression that shows the number of pieces of candy Kendra has left.

93 − 3, which is 90

Try c = 4:

Kendra has 93 pieces of candy. She gives away 4 of the pieces. Choose the expression that shows the number of pieces of candy Kendra has left.

93 − 4, which is 89

The pattern shows that in order to find the number of pieces of candy Kendra has left, you always subtract c from 93. This is the correct expression:

93 − c

let’s practice!