<span>(b+7)/2-14b= b+7/2-14b= -13b+3,5= -13*(-1)+3,5= 13+3,5= 16,5</span>
2Х + 3Y = 7
7X - 3Y = 11
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2X + 7X + 3Y - 3Y = 7 + 11
9X = 18
X = 2
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4 + 3Y = 7
3Y = 3
Y = 1
555,666,556,566,565,656,655
D=100-4×25×(-12)=100+1200=1300