Question 1011390: 10 years ago, Mona's mother was 4 times older than her daughter. After 10 years, the mother will be twice older than the daughter. Mona's present age is:
Answer by ikleyn(52781)   (Show Source):
You can put this solution on YOUR website! .
10 years ago, Mona's mother was 4 times older than her daughter.
After 10 years, the mother will be twice older than the daughter. Mona's present age is:
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Let x be the Mona's present age, and let y be the Mona's mother present age.
Ten years ago, Mona's age was x-10, and her mother's age was y-10.
Since ten years ago Mona's mother was 4 times older than her daughter, you have an equation
y-10 = 4*(x-10).
After 10 years, the mother's age will be y+10, and Mona's age will be x+10.
Since after 10 years, the mother will be twice older than the daughter, it gives you the second equation
y + 10 = 2*(x+10)
Solve this system for x and y:
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Answer. x = 20. Mona's present age is 20 years.
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