Question 1022914
Hi there,
Elizabeth is seven years older than Chloe.
E = 7 + C......(1)
Four years ago, Elizabeth was twice as old as Chloe was. 
E - 4 = 2(C - 4).....(2)
Replace 'E' in Eq(2) with '7 + C' from Eq(1)
7 + C - 4 = 2(C - 4)
7 + C - 4 = 2C - 8
Collect like terms.
C - 2C = - 8 + 4 - 7
- C = - 11
Multiply both sides by -1
C = 11
Elizabeth is 18 years old
Chloe is 11 years old.
Hope this helps :-)