Question

Como resolver x+y=7 x-y=11

Answer 1

*x+y=7   
x-y=11
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2x= 18
x=18/2
x=9

*x+y=7  
9 + y=7
y= 7-9
y= -2

S=( 9,-2)

Answer 2

   x+y=7
   x-y=11
    2x = 18
      x = 9

    x + y =7
      y = 7 - x ==> y= 7 - 9 ==> y - 2