Explanation:
To simplify the expression 5/9z - 6/9z + 3 - 7/9z, we can first combine the like terms with the same variable coefficient. The terms 5/9z, -6/9z, and -7/9z all have the variable z, so we can add them together to get:
(5/9z) + (-6/9z) + (-7/9z) = (-8/9z)
Now we can substitute (-8/9z) back into the original expression in place of the three z terms we just combined:
5/9z - 6/9z + 3 - 7/9z = (5/9z) + (-6/9z) + (3) + (-7/9z)
= -8/9z + 3
Therefore, the simplified form of the expression is -8/9z + 3.