Question 1109342
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The problem says her dad is "3 times older than" Rachel, meaning the difference in their ages is 3 times Rachel's age.  (It does NOT mean that her dad is 3 times AS OLD AS her.)<br>
So the difference in their ages is 3 times Rachel's age; but we know the difference in their ages is 30 years.  So Rachel's age is 10; that makes her dad 40.<br>
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Note: The answer by tutor stanbon -- that Rachel's dad is 45 years old -- is PROBABLY the answer the author of the problem wanted.<br>
However, the right answer, using the grammatically correct interpretation of the given information, is that her dad is 40.<br>
The problem is with the phrase saying that her dad is "3x older" than Rachel.<br>
While everyday sloppy usage treats that the same as "3x as old", they mean different things.<br>
For "3x as old", you obviously just multiply by 3.<br>
But the grammatically correct interpretation of "3x older" is that her Dad is her age, plus 3 more times her age -- i.e., 4 times AS OLD.