SOLUTION: john is now 4 times as old as his brother sam. in 4 years, john will be twice as old as sam will be then. find their present ages.

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Question 241577: john is now 4 times as old as his brother sam. in 4 years, john will be twice as old as sam will be then. find their present ages.
Answer by College Student(505) About Me  (Show Source):
You can put this solution on YOUR website!
John is now 4 times as old as his brother Sam, so...
Let Sam = x
Let John = 4x
.
In 4 years, John will be twice as old as Sam will be then. Our equation now becomes: John in 4 years = twice Sam in 4 years
4x%2B4=2%28x%2B4%29
Now solve for x to determine Sam's age.
4x%2B4=2x%2B%282%2A4%29
4x%2B4=2x%2B8
4x-2x=8-4
2x=4
x=2 ...this is Sam's age (today)
.
4x=4%2A2=8 ...this is John's age (today)
.
Now let's plug the x value in the original equation to see if it makes sense.
Remember: 4x%2B4=2%28x%2B4%29
4%282%29%2B4=2%282%2B4%29
8%2B4=%282%2A2%29%2B%282%2A4%29
12=4%2B8
12=12 ...the x value checks!
.
Done!