SOLUTION: In 3 years, Jeff will be twice as old as he was 4 years ago. How old is Jeff now?

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Question 846790: In 3 years, Jeff will be twice as old as he was 4 years ago. How old is Jeff now?
Found 2 solutions by josh_jordan, jim_thompson5910:
Answer by josh_jordan(263) About Me  (Show Source):
You can put this solution on YOUR website!
To solve, we need to set this word problem up as an equation. Let's break down each word (series of words):

In 3 years: + 3

Jeff: J

will be: =

twice as old as he was 4 years ago = 2(J - 4)

Now let's put all of this together:

J + 3 = 2(J - 4)

Now we have an equation we can solve. First, distribute the 2 to (J - 4):

J + 3 = 2J - 8

Subtract J from both sides of the equal sign:

J - J + 3 = 2J - J - 8 ----->

3 = J - 8

Finally, add 8 to both sides of the equal sign:

3 + 8 = J - 8 + 8 ----->

11 = J

Therefore, Jeff is 11 years old.


Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = Jeff's current age right now

He is currently x years old

In 3 years, he will be x+3 years old.

Four years ago, he was x-4 years old.

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"In 3 years, Jeff will be twice as old as he was 4 years ago" means that x%2B3+=+2%28x-4%29

Solve for x to get...

x%2B3=2%28x-4%29 Start with the given equation.


x%2B3=2x-8 Distribute.


x=2x-8-3 Subtract 3 from both sides.


x-2x=-8-3 Subtract 2x from both sides.


-x=-8-3 Combine like terms on the left side.


-x=-11 Combine like terms on the right side.


x=%28-11%29%2F%28-1%29 Divide both sides by -1 to isolate x.


x=11 Reduce.


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Answer:

So the solution is x=11

This means that Jeff is currently 11 years old.