Question 711598
Amy is twice as old as Lucy. 
SO let lucy is x then amy is 3x
Three years from now 
lucy is x+3 then amy is 3x+3
the sum of their ages will be 42.
so x+3+3x+3=42
or 4x+6=42
or 4x=42-6=36
or x=36/4=9
so lucy is 9 yrs and amy is 27 yrs