X и у стороны
<img src="http://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7Bx-y%3D3%7D+%5Catop+%7Bx%2By%3D27%7D%7D+%5Cright.+%5C%5C%0A%5C%5C%0A+%5Cleft+%5C%7B+%7B%7Bx%3D3%2By%7D+%5Catop+%7B2y%2B3%3D27%7D%7D+%5Cright.%5C%5C%0Ay%3D12%5C%5C%0Ax%3D15%5C%5C%0AS%3D12%2A15%3D180» id=»TexFormula1″ onerror=»texError(this)» title=» left { {{x-y=3} atop {x+y=27}} right. \
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left { {{x=3+y} atop Ӑy+3=27}} right.\
y=12\
x=15\
S=12*15=180″ alt=» left { {{x-y=3} atop {x+y=27}} right. \
\
left { {{x=3+y} atop Ӑy+3=27}} right.\
y=12\
x=15\
S=12*15=180″ align=»absmiddle» class=»latex-formula»>