Can someone walk me through how this expression simplifies to y/x? I am just wondering how this equation comes to be: it is from an economics problem involving marginal utilities. I have my two variables, $x$ and $y$. 
Intuitively, how does $$\frac{0.5\times x^{-0.5}\times y^{0.5}}{0.5\times x^{0.5}\times y^{-0.5}}= \frac{y}{x}?$$
I'm guessing that the $0.5$ and $(1/2)$ both cancel out, but I am not sure what happens next.
Thank you!

Let me show you. It's just the "Multiply by one" trick:
$\frac{0.5 x^{-\frac{1}{2}} y^\frac{1}{2}}{0.5 x^\frac{1}{2} y^{-\frac{1}{2}}} \cdot 1 \cdot 1 = \frac{0.5 x^{-\frac{1}{2}} y^\frac{1}{2}}{0.5 x^\frac{1}{2} y^{-\frac{1}{2}}} \cdot \frac{y^\frac{1}{2}}{y^\frac{1}{2}} \cdot \frac{x^\frac{1}{2}}{x^\frac{1}{2}}$
You know, of course, that $a^p a^q = a^{p+q}$:
$\frac{0.5 x^{-\frac{1}{2}+\frac{1}{2}} y^{\frac{1}{2}+\frac{1}{2}}}{0.5 x^{\frac{1}{2}+\frac{1}{2}} y^{-\frac{1}{2}+\frac{1}{2}}}=\frac{0.5x^0 y^1}{0.5x^1 y^0} = \frac{y}{x}$
And there you have it :)
