Answer:
Step-by-step explanation:
x+4y=6
x+4y=15
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x+4y=6
-(x+4y)=-15
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x+4y=6
-x-4y=-15
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0=-9
no solution
Answer: No Solution
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x+4y=7
3x+12y=21
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simplify 3x+12y=21 into x+4y=7
Answer: Infinitely many solutions
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x-y=1
2x+y=4
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x=y+1
2(y+1)+y=4
2y+2+y=4
3y=4-2
3y=2
y=2/3
x-2/3=1
x=1+2/3
x=3/3+2/3=5/3
Answer: x=5/3, y=2/3. (5/3, 2/3).
