21* (y-8)=84
у-8=84/21
у-8=4
у=4+8
у=12
(x+67):18=4
18*4=х+67
х+67=72
х=72-67
х=5
(16m+5m):18=7
16m+5m=18*7
21m=126
m=126/21
m=6
(17n-8n)*13=351
17n-8n=351/13
9n=27
n=27/9
n=3
21* (y-8)=84
у-8=84/21
у-8=4
у=4+8
у=12
(x+67):18=4
18*4=х+67
х+67=72
х=72-67
х=5
(16m+5m):18=7
16m+5m=18*7
21m=126
m=126/21
m=6
(17n-8n)*13=351
17n-8n=351/13
9n=27
n=27/9
n=3