Carcass wrote:
Jim is twice as old as Stephanie, who, four years ago, was three times as old as Kate. If, five years from now, the sum of their ages will be 51, how old is Stephanie ?
A. 6
B. 10
C. 14
D. 20
E. 24
Here's an algebraic approach.
Let x = Stephanie's present age.
James is twice as old as StephanieSo 2x = James' present age.
4 years ago, Stephanie's was 3 times as old as KateIn other words, 4 years ago, Kate's age was 1/3 of Stephanie's age.
4 years ago, Stephanie'sage was x-4, so Kate's age
4 years ago, was (x-4)/3
So, Kate's
present age = (x-4)/3 + 4
In 5 years . . .
Stephanie's age = x + 5
James' age = 2x + 5
Kate's age = (x-4)/3 + 4 + 5
5 years from now, the sum of their ages will be 51So (x + 5) + (2x + 5) + (x-4)/3 + 4 + 5 = 51
Simplify: 3x + (x-4)/3 + 19 = 51
Subtract 19 from both sides: 3x + (x-4)/3 = 32
Multiply both sides by 3: 9x + (x-4) = 96
Solve . . . x = 10
Answer: B