Meaning of Open Sentence ( Primary School Algebra for Grade 4 )

# Meaning of Open Sentence ( Primary School Algebra for Grade 4 )

An open sentence is a mathematical statement showing two equal expressions and containing a missing quantity to be found. The missing quantity is usually represented by an empty box, a blank line or a letter x.

Examples
a. 8 + ( _ ) =40
b. 85 - ( _ )=33
c. 4 × ( _ )=24
d. 1/4 of ( _ )=2

a. 8+( )=40, let ( ) be t
8 + t   = 40

t = 40-8
t= 32
: . 8 + ( 32 ) = 40

b. 85-( )=33, let ( ) be x

85 - x = 33
85 -33 = x
52 = x
:.85-(52)=33

a. 8+( )=40, let ( ) be t
8 + t   = 40

t = 40-8
t= 32
: . 8 + ( 32 ) = 40

b. 85-( )=33, let ( ) be x

85 - x = 33
85 -33 = x
52 = x
:.85-(52)=33

c. 4×( )=24 , let the ( ) be x
x = 24÷4
x = 6
: . 4 × (6) =24

d. 1/4 of ( )=2 , let ( ) be y

1/4 × y = 2
y = 2÷ 1/4 { 2×4/1}
y = 8
: . 1/4 of (8) = 2

For questions 1 to 4, find the missing number in each of the given open sentences.
1. 92 + 17=( )
2. 6 × ( )=18
3. 12 ÷ ( )=6
4. 44 - 42 =( )