One third of the number and one seventh of a number equal 6/7. What is the number?

Question

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Answer 1

1/3* X + 1/7 * X = 6/7

 

7X + 3X = 18  <---- multiplies everything by 21 to clear the fractions

 

10X = 18

 

X = 18/10 = 9/5

 

CHECK:  1/3*9/5 + 1/7*9/5 =

 

                  9/15 +     9/35 =

 

                  3/5   +     9/35 =

 

                21/35 +     9/35 =

 

                     30/35 = 6/7

 

The number is 9/5