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 January 7th, 2017, 06:22 PM #2 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,657 Thanks: 964 Math Focus: Elementary mathematics and beyond x + y = 15 x (4%) + y (1%) = 15(2%) Try multiplying the second equation by 100. Thanks from Indigo28
January 7th, 2017, 06:34 PM   #3
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Quote:
 Originally Posted by greg1313 x + y = 15 x (4%) + y (1%) = 15(2%) Try multiplying the second equation by 100.
So if I multiply .04x + .01y by 100, I get 4x + 1y = 30.

And then the answer to that is also (5,10)...

So, are you saying to use the second equation multiplied by 100 rather than the original one to add them?

x + y = 15
+ 4x + 1y = 30
_________________
5x + 3y = 45

Is that what you meant?

 January 7th, 2017, 06:38 PM #4 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,657 Thanks: 964 Math Focus: Elementary mathematics and beyond x + y = 15 4x + y = 30 Think! What if you subtract them? Thanks from Indigo28
 January 7th, 2017, 06:46 PM #5 Senior Member   Joined: Jan 2017 From: US Posts: 104 Thanks: 5 Ooooohhhh ok, gotcha. I really am new enough to this, that I did not even know subtracting them was an option. So: 4x + 1y = 30 - x + y = 15 ______________ 3x = 15 x=5 5 + y = 15 5(4%) + y (1%) = 15(2%) 5 + 10 = 15 5(4%)+ 10(1%) = .30 So x= 5 and y= 10. Thank you! Thanks from greg1313
 January 7th, 2017, 07:08 PM #6 Global Moderator   Joined: Dec 2006 Posts: 18,232 Thanks: 1437 To preserve spacing, you can enclose text between [code] and [/code] as shown below. Code:  4x + 1y = 30 - x + y = 15 ___________ 3x = 15 Thanks from Indigo28
January 7th, 2017, 07:24 PM   #7
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Quote:
 Originally Posted by skipjack To preserve spacing, you can enclose text between [code] and [/code] as shown below. Code:  4x + 1y = 30 - x + y = 15 ___________ 3x = 15
Thanks skipjack! I didn't know that so I will definitely do it in the future!

 January 8th, 2017, 07:57 AM #8 Newbie   Joined: Jan 2017 From: Georgia Posts: 10 Thanks: 3 Try to only get one variable by using substitution or elimination. Here's a link that might help: https://www.khanacademy.org/math/alg...s-of-equations Thanks from Indigo28
 January 9th, 2017, 03:35 AM #9 Member   Joined: Sep 2016 From: India Posts: 88 Thanks: 30 Write both equations $x+y=15......(1)$ $0.04x+0.01y=0.30.....(2)$ Multiplying equation(1) by $0.04$ we get $0.04x+0.04y=0.60.....(3)$ Now, subtracting equation(2) from equation(3) we get $0.03y=0.30$ $y=10$ Putting value of $y$ in equation(1) we get $x+10=15$ $x=5$ Hence, $x=5,\;\;\;\;\;\;\; y=10$ Thanks from Indigo28

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