This seems like a simple question, but I can't solve it

Expand the fraction

$$\frac{s+1}{s+2}$$

Mathematica says it is $1-\frac{1}{s+2}$

But how?

Take

$$\frac{s+1}{s+2}=\frac{s}{s+2}+\frac{1}{s+2}$$

But then, how do you simplify further?

Thanks