216 : (16 - х) = 18 5у + 3(7у + 18) = 106
16 - х = 216 : 18 5у + 21у + 54 = 106
16 - х = 12 26у = 106 - 54
х = 16 - 12 26у = 52
х = 4 у = 52 : 26
у = 2
8х + 4(13х + 32) = 308 5(11х - 31) - 9х = 121
8х + 52х + 128 = 308 55х - 155 - 9х = 121
60х = 308 - 128 46х = 121 + 155
60х = 180 46х = 276
х = 180 : 60 х = 276 : 46
х = 3 х = 6
складываем
11 4/13+8 5/26=
19+(8/26+5/26)=
19 13/26=19 1/2
4 7/45+10 2/5=
14+(7/45+18/45)=
14+25/45=14 5/9
19 1/2+14 5/9=33 +(9/18+10/18)=33 19/18=34 1/18