Let’s start with simplifying the numbers
21/14
There’s a common factor of 7, so you can divide each by 7
21/7=3 and 14/7=2
So 21/14=3/2
Now let’s simplify x
Using the exponent rule
x^a / x^b = x^(a-b)
So x^6 / x^2 = x^(6-2) = x^4
Next let’s simplify y using the same exponent rule
y^5 / y^9 = y^(5-9) = y^(-4) = 1/y^4
Multiply it all together
(3/2) * (x^4) * (1/y^4) = 3x^4 / 2y^4
Hope this helps