Question 865184: HELP!!!!
9a+10b+12c=398
6a+4b+4c=164
1a+2b+1c=58
Solve for a,b,c and show work!
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! 9a + 10b + 12c = 398
6a + 4b + 4c = 164
1a + 2b + 1c = 58
Multiply the 1st equation by-1, the 3rd equations by 3
-9a - 10b - 12c = -398
6a + 4b + 4c = 164
3a + 6b + 3c = 174
---------------------Addition eliminates a & b, find c
0a + 0b - 5c = -60
c = -60/-5
c = +12
:
using the 2nd and third equations replace c with 12
6a + 4b + 4(12) = 164
1a + 2b + 1(12) = 58
:
6a + 4b = 164 - 48
1a + 2b = 58 - 12
:
6a + 4b = 116
1a + 2b = 46
multiply the 2nd equation by -2
6a + 4b = 116
-2a - 4b = -92
-----------------addition eliminates b, find a
4a = 24
a = 24/4
a = 6
:
Use the original 3rd equation to find b
1a + 2b + 1c = 58
6 + 2b + 12 = 58
2b = 58 - 18
2b = 40
b = 40/2
b = 20
:
You can confirm this for yourself in the 1st and 2nd equation
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