Greetings from Brasil...
The expression that allows you to calculate the distance between two points is:
d(A; B) = √[(Xb - Xa)² + (Yb - Ya)²]
Bringing to our problem:
d(A; B) = √[(0 - 3)² + (- 3 - 1)²]
d(A; B) = √[(- 3)² + (- 4)²]
d(A; B) = √[9 + 16]
d(A; B) = √[25]
d(A; B) = 5