Question 72868
You ask for a formula, I guess it would be 

u^x/u^y = u^x-y

Another words you just subtract the exponents.

To solve the problem:
Simplify -24/-18 by dividing both by 6, to 4/3

u^4/u^1 = u^3 (subtract 4-1)

v^3/v^5 = v^-2 (subtract 3 - 5)

x^5 - x^2 = x^3

When you put it all together you have 
(4/3)u^3v^-2x^3

Which can also be written as a fraction:
4u^3x^3
________
3v^2