SOLUTION: I'm trying to help my children with this problem, but cannot figure it out. My only conclusion is that the teacher manual is wrong about this problem.
Problem:
Mr. black is thr
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-> SOLUTION: I'm trying to help my children with this problem, but cannot figure it out. My only conclusion is that the teacher manual is wrong about this problem.
Problem:
Mr. black is thr
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Question 589535: I'm trying to help my children with this problem, but cannot figure it out. My only conclusion is that the teacher manual is wrong about this problem.
Problem:
Mr. black is three times as old as his son Jerry. Nine years ago he was nine times as old as Jerry.
Answer supose to be:
3X-9=9(x-9)
How do they come to this solution? Found 2 solutions by stanbon, John10:Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! Problem:
Mr. black is three times as old as his son Jerry. Nine years ago he was nine times as old as Jerry.
Answer supose to be:
3X-9=9(x-9)
How do they come to this solution?
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Equations based on the problem description.
b = 3j
(b-9) = 9(j-9)
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Substitute for "b" and solve for "j":
(3j-9) = 9(j-9)
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That is the equation you are asking about.
I used "j" to represent Jerry's current age;
the book uses "x" for the same representation.
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Cheers,
Stan H.
You can put this solution on YOUR website! Hello,
I will call Mr. Black's age is x and Jerry's age is y.
Mr. Black is three times as old as Jerry: x = 3y
"Nine years ago he was nine times as old as Jerry"
9 years ago, Mr. Black's age was (x - 9) and his son Jerry's age was ( y - 9)
so we have the second equation: (x - 9) = 9(y - 9)
so we have two equations:
x = 3y
(x - 9) = 9(y - 9)
We will substitute x = 3y into the second equation to find y:
(3y - 9) = 9(y - 9)
3y - 9 = 9y - 81
3y - 9y = 9 - 81
-6y = -72
y = -72/-6
y = 12
And we know x = 3y
so x = 3(12) = 36
Thus Mr. Black's age is 36 years old and Jerry is 12 years old.
Hope it helps you:)
John10
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