How to solve imaginary numbers

Let's say that you have the number (1 / (1+i))

and you want to solve it

you multiply this fraction up and down by the conjugate of the complex number

(1 / (1+i)) (1-i/1-i)

then it will be

1-i/1-i^2

and since i^2=-1

then it will be

1-i/2 = (1/2) - (1/2) i