You can put this solution on YOUR website! (216/27) to the power of -2/3
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(216/27)^(-2/3)
The negative means "invert"
You get:
(27/216)^(2/3)
The 3 means"take the cube root"
You get:
(3/6)^2
The 2 means "square.
(1/2)^2 = 1/4
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Cheers,
Stan H.