Answer
This prediction is reasonable.
Work Step by Step
$\lceil 12b + 66a = 831$
$\lfloor 66b + 506a = 5643$
$\lceil12\quad 66\quad\enspace \vdots \quad 831 \rceil$
$\lfloor66\quad506\quad \vdots\enspace 5643\rfloor$
$y= 7.5t + 28$
In 2020, the number of new cases of the waterborne disease will be $y= 7.5(15) + 28 = 140.5 \approx 141 $
cases.
Because the data values increase in a linear manner, this prediction is reasonable.
