Question 64936
You have done all the hard work but you have added rather than subtracted.
The minus(3a-2) needs the -1( the 1 is implied) multiplied by the (3a-2) to give -3a+2.
When you do the subtraction you end up with 2a-10 on the top which factorises to give 2(a-5) and the (a-5) will cancel with the one on the bottom.

I haven't given full instructions as you obviously know what you are doing and a small hint should be enough.