Question 50833
2(-n+4)-5=2n+5  

Distribute first.
2 * -n = -2n
2 * 4 = 8

So you have:
-2n+8-5
(add the 8 and 5)
-2n+3=2n+5

Move the 3 over to the right, making it negative.
-2n=2n+2

Then move the positive 2n to the left and add like terms:

-4n=2

Divide by -4

n=-1/2