You can not solve it as there is no equation to solve however to write this in its simplest form you need to have a common denominator of the fractions.
We can see that x²-4 could be written as (x-2)(x+2) and therefore know we have to multiply the second part of the expression by (x+2)/(x+2) to get (x²-4) on the bottom.
Now we have:
(10x+9)/(x²-4)-(3(x+2))/(x²-4)
This can also be written as:
((10x+9)-3(x+2))/(x²-4)
Now we can expand and simplify to get:
(7x+3)/(x²-4)
