Question 88885
Solve by any convenient method : 
4x + 12y = 24
2x + 6y = 12
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Multiply the 2nd equation by 2 and you will see the two equations are the same.
So the solution for the system of equations is 2x+6y=12 
or x+3y=6 or y=-(1/3)x+2
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Solve by any convenient method : 
8x + 4y =7
x = 2-2y 
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Substitute x=2-2y into the 1st equation to solve for y:
8(2-2y)+4y=7
16-16y+4y=7
-12y = -9
y = 3/4
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Solve by Elimination : 
2x -3y =-1
3x + y =15 
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Multiply the 2nd equation by 3 to get:
9x+3y=45
Add that to the 1st equation so you can solve for x:
11x=44
x=4
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Substitute that into 3x+y=15 to solve for y:
3*4+y=15
y = 3
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Solve by Substitution : 
3x + 8y = 7
x- 4y =9
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Solve the 2nd equation for x: x=4y+9
Substitute into the 1st equation so you can solve for y:
3(4y+9)+8y = 7
12y+27+8y = 7
20y = -20
y = -1
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Substitute that into x=4y+9 to solve for x:
x=4*-1+9
x=5
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cheers,
Stan H.