Answer:
24.065 miles
Step-by-step explanation:
Antonio visited three cities on the coordinate grid at A(4, 5), B(-1, 3) and C(-3, -4), he visited the cities and ended up where he started. That means he moved from point A to B to C and back to A.
The distance (d) between two points (x₁, y₁) and (x₂, y₂) can be given as:

Therefore distance between AB = 
distance between BC = 
distance between CA = 
The total distance = AB + BC + AC = 5.385 + 7.28 + 11.4 = 24.065 miles