Answer:
a = 1/6
Explanation:
You want to know the solution for the equation ...
1/(3a²) -1/a = 1/(6a²)
Solution
Multiply by a² to get the variable out of the denominator.
1/3 -a = 1/6
a = 1/6 . . . . . . add a-1/6
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Additional comment
The factor 'a' in the denominator of the original equation means 'a' cannot be zero. Fortunately, a=0 did not show up as a solution.