Simplify 6/7c -5/9d-1/2c +1/3d

To simplify the expression 6/7c - 5/9d - 1/2c + 1/3d, we need to combine like terms.

First, let's combine the terms with the variable c:
6/7c - 1/2c = (6/7 - 1/2)c

To find a common denominator for 7 and 2, we multiply 7 and 2 together, which equals 14. So now we have:
(6/7 - 1/2)c = (12/14 - 7/14)c = (5/14)c

Now, let's combine the terms with the variable d:
-5/9d + 1/3d = (-5/9 + 1/3)d

To find a common denominator for 9 and 3, we multiply 9 and 3 together, which equals 27. So now we have:
(-5/9 + 1/3)d = (-15/27 + 9/27)d = (-6/27)d

To simplify the expression further, we can simplify the fractions:
(5/14)c - (6/27)d

Now, we can find a common denominator for 14 and 27, which is 378, and multiply each fraction by the appropriate factor to get this denominator:
(5/14)c - (6/27)d = (135/378)c - (84/378)d

Therefore, the simplified expression is (135/378)c - (84/378)d.