(2a^2-10a+8)/(4-a) multiply top and bottom by -1
(-2a^2 + 10a - 8) / (a + 4) now everything is in standard order
The possible factors are 1,4,8 and the negatives.
you can do long division or synthetic division at htis point.
If you need further help ask again.
_-2a____- 2____________
a + 4 ) -2a^2 + 10a -8
-2a^2 - 8a
2a - 8 bring down the minus 8
-2a - 8 no remainder therefore it is a factor