Since the distance towards east is represented by a positive integer, the distance travelled towards west will be represented by a negative integer.
Distance travelled in east direction = 20 km
Distance travelled in west direction = -30 km
Distance travelled from A = 20 + (-30) = -10km
Therefore, we will represent the distance travelled by Rita from point A by a negative integer, i.e., -10 km (i.e., Rita is now in west direction).