susan weiberg
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- Joined
- Dec 15, 2005
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Here is my problem, trying to help my son with math homework, how do I solve:
x/4 + 3x/5 = 17
x/4 + 3x/5 = 17
Need help asap with this problem
- Thread starter susan weiberg
- Start date
Your objective here is to try and get x alone, to do that you must see what is happening to it.
First part of the problem states: x/4
You must do the opposite of this division and multiply both sides of the equation by 4
(x/4 + 3x/5)4 = (17)4
leaves you with:
x+12x/20= 68
Now you see the 12x is being divided by 20, so again muliply both sides by 20
(x+12x/20)20=68
20x+12x=1360
Combine you x's
32x=1360
Divide both sides by 32
You should get x= 42.5
I hope this helps. Reply back if something is unclear
First part of the problem states: x/4
You must do the opposite of this division and multiply both sides of the equation by 4
(x/4 + 3x/5)4 = (17)4
leaves you with:
x+12x/20= 68
Now you see the 12x is being divided by 20, so again muliply both sides by 20
(x+12x/20)20=68
20x+12x=1360
Combine you x's
32x=1360
Divide both sides by 32
You should get x= 42.5
I hope this helps. Reply back if something is unclear
susan weiberg
New member
- Joined
- Dec 15, 2005
- Messages
- 2
I'm a mom helping my son and it is totalling unclear. The only thing I know to do to check for correctness to it plug in the answer 42.5 for x in the problem and it doesn't work.
42.5/4 + 3(42.5)/5 = 17
10.625 + 127.5/5 = 17
10.625 + 25.5 = 17
36.125 = 17 Not correct
I come up with the answer of x=20
20/4 + 3(20)/5 = 17
5 + 60/5 = 17
5 + 12 = 17
17=17
How is this wrong?[/url]
42.5/4 + 3(42.5)/5 = 17
10.625 + 127.5/5 = 17
10.625 + 25.5 = 17
36.125 = 17 Not correct
I come up with the answer of x=20
20/4 + 3(20)/5 = 17
5 + 60/5 = 17
5 + 12 = 17
17=17
How is this wrong?[/url]
G
Guest
Guest
Hockeyman made a slight mistake when multiplying by 4, he multiplied top AND bottom instead of just the top.
If 20 works in the formula then it must be correct. :lol:
If 20 works in the formula then it must be correct. :lol:
Hello, Susan!
Multiply through by the LCD (least common denominator), 20.
. . \(\displaystyle \L^5\not{20}\left(\frac{x}{\not{4}}\right)\,+\,^4\not{20}\left(\frac{3x}{\not{5}}\right)\:=\:20\cdot17\)
. . . . . . . . . . . . \(\displaystyle \L5x\,+\,12x\:=\:340\)
. . . . . . . . . . . . . . . . . . . \(\displaystyle \L17x\:=\:340\)
. . . . . . . . . . . . . . . . . . . . . .\(\displaystyle \L x\:=\:20\)
When given an equation with fractions, get rid of the fractions immediately!
Multiply through by the LCD (least common denominator), 20.
. . \(\displaystyle \L^5\not{20}\left(\frac{x}{\not{4}}\right)\,+\,^4\not{20}\left(\frac{3x}{\not{5}}\right)\:=\:20\cdot17\)
. . . . . . . . . . . . \(\displaystyle \L5x\,+\,12x\:=\:340\)
. . . . . . . . . . . . . . . . . . . \(\displaystyle \L17x\:=\:340\)
. . . . . . . . . . . . . . . . . . . . . .\(\displaystyle \L x\:=\:20\)
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Re: Goodjob
:roll:
Eliz.
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:roll:
Eliz.