12-7 21/29+х+4 23/29=12 2/29
х=12 2/29-12+7 21/29-4 23/29
х=3
12-224/29+x+139/29=350/29
348/29-224/29+139/29-350/29=-x
-87/29=-x
-3=-x
x=3.
12-7 21/29+х+4 23/29=12 2/29
х=12 2/29-12+7 21/29-4 23/29
х=3
12-224/29+x+139/29=350/29
348/29-224/29+139/29-350/29=-x
-87/29=-x
-3=-x
x=3.