Question 1131176
Let E = Elizabeth's age, C = Cathrine's age
Elizabeth is twice as old as Cathrine:
E = 2C
Seven years ago their ages were E - 7 and C - 7 and their sum was 82:
E - 7 + C - 7 = 82
Substitute for E from the 1st equation:
2C - 7 + C - 7 = 82
3C = 96
C = 32
Thus Cathrine is 32 and Elizabeth is 64