fraction addition

Question

 you have 2 length of cable one is 3 5/6m and one is 1 1/4m

 

how many metres do you have? 

Answer 1

We need to add the lengths.  Before we do that, need to convert the mixed numbers into an improper fraction.  To do this, we multiply the whole number by the denominator, and add the result to the numerator.  This is our new numerator.  Keep the denominator.

 

3 5/6 = 23 / 6

 

1 1/4 = 5 / 4

 

 

 

(23 / 6) + (5 / 4)

 

We cannot add fractions with uncommon denominators.  We need find to the LCD.  LCD is 12.

 

 

(46 / 12) + (15 / 12) = 61 / 12

 

 

 

Next, we can change this improper fraction into a mixed number.  We do this by dividing the numerator by the denominator.  Using long division

 

 

        5  1/12

     ______

12 | 61

       60

      ____

          1

 

 

You have 5 1/12 metres.