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# x + y - z what is the value of this expression when x=1/3 y=3/4 and z=3/18

What is the value of the expression..just double checking my answer

### 2 Answers by Expert Tutors

Ralph L. | Algebra I, II, Visual Basic, Beginning C++ tutorAlgebra I, II, Visual Basic, Beginning C...
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x + y - z, x = 1/3, y = 3/4, z = 3/18

1/3 + 3/4 - 3/18

Lowest common denominator is 36

12/36 + 27/36 - 6/36 = 33/36 ----> 11/12

you could have also reduced 3/18 to 1/6 making the common denominator 12.
Maisha K. | Algebra Tutor for more than 12 years!Algebra Tutor for more than 12 years!
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Hi Chris,

To find the value of the expression, you need to replace all the variables with their known values:

x = 1/3 , y = 3/4,  z= 3/18

Substituting the values, the expression reads 1/3 + 3/4 -3/18.

To simplify, you need to combine the fractions. This can be done once you find a common denominator.You can find the lowest common denominator by listing the multiples of the denominators to search for the first common term.

Multiples of 18: 18 (Multiple of 3 not 4), 36.
36 is a multiple of 18 (18 x 1), a multiple of 4 (4 x 9), and a multiple of 3 (12 x 3).

Now, you will create equivalent fractions that have the common denominator of 36.

Starting with 1/3: to create a denominator of 36, you need multiply by a factor of 12. Multiply 12 on the numerator and denominator. 1/13 x 12/12 = 12/36

3/4: to create a denominator of 36, you need to multiply by a factor of 9. Multiply 9 on the numerator and denominator. 3/4 x 9/9 = 27/36

Finally 3/18: to create a denominator of 36, you need to multiply by a factor of 2. Multiply 2 on the numerator and denominator. 3/18 x 2/2 = 6/36

Add the numerators, 12 + 27 - 6 = 39 - 6 = 33.
You have 33/36.
This can be reduced by a factor of 3. Divide the numerator and denominator by 3.
33 / 3 = 11 and 36/3 = 12.