1)     120+x*3=375
   2)    24000 : (x-12)=80
    3)   x : 26+1654=2610   

Ответ:1)120+x*3=375x*3=375-120x*3=255x=3_/2552)24000/(x-12)=80   |*(x-12)24000=80(x-12)24000=80x-12*8024000=80x-96080x=24000+96080x=24960x=24960/80x=31212*  80------9603)x/26+1654=2610x/26=2610-1654x/26=956       |*26x=956*26x=24856 2610- 1654---------   956