Question 93720: Riza was 25 when her 1st son was born.Today, the sum of their ages is 105.How old is Riza and her son now? Answer by bucky(2189) (Show Source):
You can put this solution on YOUR website! When her son was born Riza was 25 and at that time her son was 0 years old.
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Since that time, x years have gone by. Riza is now 25 + x years old and her son is now x years old.
If you add their two ages, the result is 105. In equation form this is:
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Combining the two x terms on the left side results in:
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Then get rid of the 25 on the left side by subtracting 25 from both sides. The equation
then becomes:
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Solve for x by dividing both sides by 2 to get:
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That means that Riza's son whose age is x is 40 years old. And since the sum of their ages
is 105, then Riza must be 105 - 40 or 65 years old.
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And since Riza is now 65 years old, then 40 years ago she was 25 years old, and since her son
is now 40 years old, 40 years ago he was 0 and therefore was a new born.
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Everything seems to work out, so the answer of Riza presently being 65 and her son presently
being 40 years old is correct.
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Hope this helps you to see how you can just think your way through problems such as these.
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