SOLUTION: Neil is 4 years older than Andrea. If Neil was twice as old as Andrea four years ago. How old was Andrea

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Question 194146: Neil is 4 years older than Andrea. If Neil was twice as old as Andrea four years ago. How old was Andrea
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Let n=Neil's age NOW and a=Andrea's age NOW

So 4 years ago, their respective ages were n-4 and a-4


This makes "Neil is 4 years older than Andrea" translate to n=a%2B4 and "Neil was twice as old as Andrea four years ago" becomes n-4=2%28a-4%29

n-4=2%28a-4%29 Start with the second equation


n-4=2a-8 Distribute


a%2B4-4=2a-8 Plug in n=a%2B4


a=2a-8 Combine like terms on the left side.


a-2a=-8 Subtract 2a from both sides.


-a=-8 Combine like terms on the left side.


a=%28-8%29%2F%28-1%29 Divide both sides by -1 to isolate a.


a=8 Reduce.


So this means that Andrea is 8 years old right NOW.

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n=a%2B4 Go back to the first equation


n=8%2B4 Plug in a=8


n=12 Add


So Neil is 12 years old right NOW.