Answer
$\sum_{i=1}^{20}\dfrac{i+1}{i+2}$
Work Step by Step
For numerators the consecutive numbers starts from number $2$ to $21$ and for denominators the consecutive numbers starts from number $3$ to $22$. Therefore, these numbers can be represented by a summation symbol as:
$\sum_{i=1}^{20}\dfrac{i+1}{i+2}$