12x-7y=2
4x-5y=6
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<span>4x-5y=6</span>
y=0.8x-1.212x-7y=212x-7*(0.8x-1.2)=2
6.4x+8.4-2=0
6.4x+6.4=0
x=-6.4/6.4
x=-14x-5y=64*(-1)-5y=6
y=-10/5
<span>y=-2</span>
2(x+y)=124
1. sin a=a/2R