Question 873577
The sum of Annie’s, Bert’s and Chris’ ages is 60.

x+y+z=60...................(1)

 Annie is older than Bert by the same number of years that Bert is older than Chris.
y-z=x-y

2y-z-x=0....................(2)


 When Bert is as old as Annie is now,Annie will be three times as old as Chris is now.
the difference between Annies age and Berts age = x-y

(x-y)+y = 3z

x=3z.........................(3)

substitute x=3z in (1) & (2)
x+y+z=60
3z+y+z=60
y+4z=60...................(4)

2y-z-x =0

2y-z-3z=0

2y-4z=0
2y=4z
y=2z

3z+2z+z=60

6z=60
z=10...... Chris

y=2z
y=20...........Bert

x=30.............Annie