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Question 1144370: In 8 years a girl will be 3 years older than twice her present age. How old is she now?
3+2x=8?????
Found 3 solutions by solver91311, greenestamps, ikleyn:
Answer by solver91311(24713)   (Show Source):
Answer by greenestamps(13200)  (Show Source):
You can put this solution on YOUR website!
Be careful to convert the given information correctly into an equation to be solved.
You apparently started with
x = girl's present age
Then you did
3+2x = 3 years older than her present age
Good so far.
By the way, perhaps a better expression here would be "2x+3". "3 years older than her present age" implies that the 3 is added to twice her present age, instead of the other way around. Algebraically, they are of course the same. But the advantage of the alternate expression is for the case where the information said "3 years less than her current age". In that case, careless interpretation might lead to "3-2x", where clearly the correct expression would be "2x-3".
So now the information says that the girl's age 8 years from now will be 3 more than twice her present age. You wrote that as
3+2x = 8
But "8" is not "8 years more than her current age".
Her current age is x; what is the correct expression for "8 more than her current age"?
Put that correct expression on the right hand side of your equation and you will have an appropriate equation to solve simply to find the answer to the question.
Answer by ikleyn(52803)  (Show Source):
You can put this solution on YOUR website! .
Let "x" be her age now.
Then in 8 years her age will be (x+8) years.
From the other side, "twice her present age" is (2x), and
"3 years more than twice her present age" is this value (2x+3).
According to the condition, these two values are equal
x + 8 = 2x + 3.
It is your equation, and you want to solve it to find x.
Collect the terms with x in the right side, and collect the constant terms in the left side, like this
8 - 3 = 2x - x
5 = x,
which gives you the answer: the girl is 5 years old now.
It is a standard age word problem.
To solve a standard age word problem, always start the solution with this mantra:
Let x be the age under the question.
Then the age in "n" ears will be (x+n),
while the age "m" years ago was (x-m).
If you start the solution with the right words, then the logic inside your mind always will guide you in right direction.
/\/\/\/\/\/\/\/
There is a bunch of lessons on age word problems
- Age problems and their solutions
- A fresh formulation of a traditional age problem
- Really intricate age word problem
- Selected age word problems from the archive
- Age problems for mental solution
in this site.
Read them and become an expert in solving age problems.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Age word problems".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.
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