( ab / c ) + d = xb - c
( ab + dc ) / c = xb - c
xb = ( ( ab + dc ) / c ) + c
xb = ( ab + dc + c^2 ) / c
x = ( ( ab + dc + c^2 ) / c ) : b
x = ( ab + dc + c^2 ) / bc
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ab + d = b( x - c )
x - c = ( ab + d ) / b
x = ( ( ab + d ) / b ) + c
x = ( ab + d + cb ) / b
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a + d = d( x + c )
x + c = ( a + d ) / d
x = ( ( a + d ) / d ) - c
x = ( a + d - cd ) / d
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ab / c = xd / c
ab = xd
x = ab / d
2х+5у=1 2х+5у=1 2х+5*1=1 х=-2
2х-3у=-7 /*-1 -2х+3у=7 у=1 у=1
8у=8
у=8:8 2х+5*1=1
у=1 2х+5=1
2х=-5+1
2х=-4
х=-4:2
х=-2
Ответ:(-2;1)