Thinking Mathematically (6th Edition)

Fill the blank with: ... $P(E)=\displaystyle \frac{a}{a+b}$ ...
If odds in favor of $E$ are $a$ to $b$, then $P(E)=\displaystyle \frac{a}{a+b}$. --------- Fill the blank with: ... $P(E)=\displaystyle \frac{a}{a+b}$ ...