Hey there! I'm happy to help!
We want to get a on one side of the equation all on its own.
Let's flip the equation around so a ends up on the left. Usually variables are supposed to be on the left.
2a-2=u
We add 2 to both sides.
2a=u+2
We divide both sides by 2.
a=(u+2)/2
We divide both u and 2 by 2 so our answer is completely simplified.
a=1/2u+1.
I hope that this helps! Have a wonderful day! :D