Answer:
(-2,-1)
Explanation:
To reflect something across an axis we need to change the coordinate of the other axis. To reflect a point across the X axis we need to change the sign on the Y axis because that will put it on the other side of the X axis. In this question the 1 is what we will change from positive to negative. By doing this it will move the point from above the X axis to below the X axis.
I hope this helps and please don't hesitate to ask if there is anything still unclear!