Question 665671: I am 52,my granddaughter is 14. I was 38 when she was born (52-14=38). At some point I will be 3 times her age at that moment. Write an equation which models how old in years each of us will be when I am three times as old as my granddaughter. Explain the reasoning which helped me develop my answer.
I have started with x + 38 = (3 X 14) after this I am stuck, and after reading numerous sections in my text book, I am confusing myself. This is for an online course, so there is no vocal interaction between Instructor and pupil.
Any ideas will greatly appreciated.
Yvonne
Found 3 solutions by mananth, DrBeeee, MathTherapy:
Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website! Let x be the number of years after which the grand mother will be three times her granddaughter's age.
Today the GM is 52
after x years she will be 52+x
Today G Daughter is 14
after x years GD will be (14+x)
52+x= 3(14+x) is the equation
------------------
52+x=42+3x
3x-x=10
2x=10
x= 5
m.ananth@hotmail.ca
Answer by DrBeeee(684)  (Show Source):
You can put this solution on YOUR website! Solution has nothing to do with 38. Read your equation. Does it make sense? No
Let x = number of years from NOW
Then grandfather, g, will be 52+x years old and the granddaughter, d, will be 14+x years old. therefore, we have, x years from now
(1) 52+x = 3*(14+x) or
(2) 52+x = 42 + 3x,
Now subtract 42 from each side of (2)and get
(2a) 52 - 42 + x = 42 - 42 + 3x or
(2b) 10 + x = 0 + 3x or
(2c) 10 + x = 3x
Now subtract x from each side of (2c) and get
(2d) 10 + x - x = 3x - x or
(2e) 10 + 0 = 2x or
(2f) 10 = 2x which is the same as
(3) 2x = 10 or
(4) x = 5
Is this right? Use (1)
Is (52+5 = 3*(14+5))?
Is (57 = 3*19)?
Is (57 = 57)? Yes
Answer: The desired equation is (1). In 5 years grandfather will be 57 and his granddaughter will be 19. He will be three times as old as her.
PS see the new steps for (2) to (3).
PPS your just a baby, I'm 81, got my PhD when I was 43, so hang in there, you have more common sense than any of your young classmates. Good luck on your new career.
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
I am 52,my granddaughter is 14. I was 38 when she was born (52-14=38). At some point I will be 3 times her age at that moment. Write an equation which models how old in years each of us will be when I am three times as old as my granddaughter. Explain the reasoning which helped me develop my answer.
I have started with x + 38 = (3 X 14) after this I am stuck, and after reading numerous sections in my text book, I am confusing myself. This is for an online course, so there is no vocal interaction between Instructor and pupil.
Any ideas will greatly appreciated.
Yvonne
Let the amount of years that you will be 3 times her age be Y. At that time (Y years), you'll be 52 + Y and she'll be 14 + Y
We then can say that: 52 + Y = 3(14 + Y)
52 + Y = 42 + 3Y
Y - 3Y = 42 - 52
-2Y = - 10
Y, or amount of years when you'll be 3 times her age =  , or 
You can do the check!!!
Send comments and “thank-yous” to “D” at MathMadEzy@aol.com
|
|
|
