What is the third step of process of mathematical model?

If $$\frac{(9^n \times 3^2 \times 3^n – (27)^n )}{((3^3 )^5 \times 2^3)}$$​= $$\frac{1}{27}$$​then the value of 'n' is

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The median class of the above frequency distribution

The ascending order of the following 3/8, 38%, 0.0038, 0.308