Answer
See below.
Work Step by Step
$\frac{f(x)}{g(x)}=\frac{4x^{2/3}}{5x^{1/2}}=\frac{4}{5}\frac{x^{2/3}}{x^{1/2}}=0.8x^{2/3-1/2}=0.8x^{1/6}$
The function is undefined for negative numbers, so the domain is the non-negative real numbers.
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