<PRE><B>Question 1097676</B>
x+y=21
3/4x+2/3y=15
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y=21-x
3/4x+2/3(21-x)=15
3/4x+14-2/3x=15
9/12x-8/12x=15-14
1/12x=1
x=(1/1)/(1/12)
x=1/1*12/1
x=12
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3/4*12+2/3y=15
9+2/3y=15
2/3y=15-9
y=6/(2/3)
y=6*3/2
y=9
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x+y=21
12+9=21
</PRE>