Question 83164
First try expanding the bottom bracket (if I understand correctly the last number you put down was a power of 2)
This means that each power in the bottom expression will be multiplied by 2:
{{{(x^7y^4z^0)/(5^-4x^6y^-16z^-18)}}}
Next deal with the numbers:
{{{1/5^-4=5^4=625}}}
Then terms in x:
{{{x^7/x^6=x}}}
Then terms in y:
{{{y^4/y^-16=y^20}}}
And finally z:
{{{z^0/z^-18=z^18}}}
So it all becomes
{{{625xy^20z^18}}}