Writing Expressions
Fern has 7 red pens and b blue pens. How many pens does Fern have?
7 + b
Roger bought some used CDs at a garage sale. He gave 9 CDs to his dad and kept 12 of them for himself. How many CDs did Roger buy at the garage sale?
c - 9 = 12 or c - 12 = 9
18 + x = 36
x = 18
What value goes in the blank space?
10 + ____ = 2 x 7
4
A(n) _________________ is an unknown part of an equation, represented by a letter.
Variable
Sarah had 15 quarters. She used q quarters in the vending machine. How many quarters does Sarah have left?
15 - q
Felicia and Sam sold 103 muffins at the bake sale. Felicia sold 25 muffins. How many muffins did Sam sell at the bake sale?
25 + m = 103
m + 25 = 103
103 - m = 25
x - 45 = 43
x = 88
What value goes in the blank space?
81 ➗ 9 = 21 - ___
12
Each group of variables and numbers, separated by operation signs, is called a _____________
Term
Macy had d dollars. She gave half of her dollars to charity. How many dollars did she give to charity.
d/2
Francine walked 44 miles last month on her days off. She walked 4 miles each time. How many days did Francine have off?
4d = 44
44/d = 4
x/3 = 10
x = 30
Use the preservation of equality to determine the value of x. You need to show your work!
7 + x = 24
x = 24 - 7
x = 17
When you "balance out" an equation by doing the same operation to both sides.
Preservation of equality
A candy company divided c bags of candy into 12 boxes. How many bags of candy are in each box?
c/12
Alison took 51 candy bars and split them into groups to give out for Halloween. She put 3 bars in each group. How many bunches did Alison make?
51/b = 3
3b = 51
15x = 75
x = 5
Use the preservation of equality to determine the value of x. You need to show your work!
4x + 9 = 25
4x = 25 - 9
4x = 16
x = 16/4
x= 4
A(n) ________________ is a combination of numbers, variables, and symbols that illustrate a mathematical relationship
What is an expression?
Five times the sum of 4 and t
5(4 + t)
When added to 13, the quotient of 6 and x is equal to 15.
6/x + 13 = 15
(x/7) - 6 = 4
x = 70
Use the preservation of equality to determine the value of x. You need to show your work!
x/3 - 10 = 1
x/3 = 10 + 1
x/3 = 11
x= 11 x 3
x = 33
What are 2 main differences between expressions and equations?
Equations have an equal sign, expressions don't
Equations can be solved, expressions can only be simplified
The value of a variable can differ in expressions, in equations it needs to be a specific value