AB = 10
EF = 2
Explanation:
to find the scale factor you have to divide the bigger scale by the smaller one which would be
(5x)/5 and 4/x
since both scale factors should be the same you can set them even to each other
(5x)/5=4/x
solve for x
(5x)15=4/x
x=4/x
y^2=4
x=2