



 
Hi, First look at what is inside the parentheses, which I assume is $\left( 27^r \right)^{1}.$ This can be written $\frac{1}{27^r}.$ Hence your expression can be written \[\left( \frac{1}{27^r} \right)^\frac{2}{3}.\] The negative sign in the exponent tells me that $\left( \frac{1}{27^r} \right)$ should be inverted and hence the expression can now be written \[\left( 27^r \right)^\frac{2}{3}.\] But $27 = 3^3$ so make this substitution and simplify. I hope this helps,  


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