step 1
find the distance AB
A(1,1) B(3,0)
d=√[(y2-y1)²+(x2-x1)²]----> d=√[(0-1)²+(3-1)²]----> d=√5
step 2
find the distance JK
J (-5,-1) K(3,-5)
d=√[(-5+1)²+(3+5)²]----> d=√80
step 3
find the scale factor
scale factor=distance JK/distance AB-----> √80/√5----> 4
step 4
find the distance BC
B(3,0) C(3,3)
d=√[(3-0)²+(3-3)²]----> d=3
step 5
find the length of KL
KL=scale factor*distance BC------> 4*3=12
the answer is
the length of KL is 12 units