Answer :
х+6у =20
x+3y = 14 //-1
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х+6у =20
-x-3y = -14
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3y = 6
y = 2
x + 3(2) = 14
x + 6 = 14
x = 14 - 6
x = 8
х+6у =20
x+3y = 14 //-1
-----------------------
х+6у =20
-x-3y = -14
------------------------
3y = 6
y = 2
x + 3(2) = 14
x + 6 = 14
x = 14 - 6
x = 8