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2014-09-03T11:46:04+03:00
5x+5y+7*3=196

5x+5y=196-21

5x+5y= 175 |:5

x+y=35

7x+7y+5z= 7(x+y)+5*3

=7*35+15=

=245+15=

=260
2014-09-03T11:52:17+03:00
5X+5Y+7Z=196
Z=3
5(X+Y)=196-7X3
X+Y=175/5
X+Y=35
7(X+Y)+5X3=7X35+15=260