U=-2a-3/ka
First you need to get rid of the denominator. Do this by multiplying each side by ka.
U(ka) = -2a - 3
Now add 2a to both sides.
Uka + 2a = -3
You can factor this because you have a common variable.
a(Uk + 2) = -3
Now you can divide both sides by (Uk + 2).
a = -3/(Uk + 2)
And that is your answer.
