we know that
the rule of the translation is
[tex](x,y)------> (x+2,y+1)[/tex]
that means
the translation is [tex]2[/tex] units to the right and [tex]1[/tex] unit up
Let
[tex]A(0,0)\\B(1,3)[/tex]
Step 1
Find the coordinates of A'
[tex]A(0,0)------> A'(0+2,0+1)[/tex]
[tex]A(0,0)------> A'(2,1)[/tex]
Find the coordinates of B'
[tex]B(1,3)------> B'(1+2,3+1)[/tex]
[tex]B(1,3)------> B'(3,4)[/tex]
Step 2
Find the distance A'B'
we know that
the formula to calculate the distance between two points is equal to
[tex]d=\sqrt{(y2-y1)^{2}+(x2-x1)^{2}}[/tex]
we have
[tex]A'(2,1)\\B'(3,4)[/tex]
substitute in the formula
[tex]d=\sqrt{(4-1)^{2}+(3-2)^{2}}[/tex]
[tex]dA'B'=\sqrt{10}\ units[/tex]
therefore
the answer is
the distance A'B' is [tex]\sqrt{10}\ units[/tex]