3х+12=0 8х-5=х-40 9+13у=35+26у 8у-(7у-142)=51 9с+2,65=36,85-9с

3x+12=0 8x-5=x-40
3x= -12 8x-x =-40+5
x= -4 7x= -35
x= -5
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9+13у=35+26у 8у-(7у-142)=51
13y-26y=35-9 8y-7y+142=51
-13y=26 y+142=51
y= -2 y= -91

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9с+2,65=36,85-9с
9c+9c=36.85+2.65
18c=39.5
c=95.5/18
c= $\frac{79}{2} / \frac{1}{18}$
c=2 $\frac{7}{36}$