Question 1123826: Ten years ago, the sum of the ages of a mother and her daughter was seventy years. This year the mother is twice as old as her daughter. What will be the age of the daughter in ten years time?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39616)   (Show Source):
Answer by MathTherapy(10551)  (Show Source):
You can put this solution on YOUR website! Ten years ago, the sum of the ages of a mother and her daughter was seventy years. This year the mother is twice as old as her daughter. What will be the age of the daughter in ten years time?
If 10 years ago, their ages summed to 70, then today, their ages sum to 70 + 2(10) = 90
Therefore, let the daughter's age be D
Then mother's is 90 - D
We then get: 90 - D = 2D
90 = 3D
D, or daughter is 
In 10 years' time, daughter will be: 
OR
If their ages summed to 70, 10 years ago, then in ten years' time, their ages will sum to 70 + 2(20), = 110 years
Let daughter's age, 10 years from now, be D
Then mother's then, would be 110 - D
We then see that today, daughter will be D - 10, and mother will be 110 - D - 10, or 100 - D
We then get: 100 - D = 2(D - 10)
100 - D = 2D - 20
- D - 2D = - 20 - 100
- 3D = - 120
D, or daughter, in 10 years, will be: 
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