Answer: 13 units
Explanation:
The distance formula to calculate distance between two points (a,b) and (c,d) is given by :-

Given points : (13, 20) and (18, 8)
Now, the distance between the points (13, 20) and (18, 8)is given by ;-

Hence, the distance between the points (13, 20) and (18, 8) is 13 units.