MYTS 2018 — Grade 8 — Round 1 Question 10

Farms $A,B,C,D$ lie in order on a straight road, with $AB=2$ km, $AC=5$ km and $AD=6$ km. Place a factory on the road so its distances to $A,B$ sum to its distances to $C,D$. How far is it from $A$, in km?