Question 207645
A)
x-3y=7, x=3y+7
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-3x+16y=28
-3(3y+7)+16y=28
-9y-21+16y=28
7y=49
y=7
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x-3y=7
x-3(7)=7
x-21=7
x=28
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-3(28)+16(7)=28
-84+112=28
You try the others
Good luck
Bob