Мне 3* х-7800=1200 (у+2958): 57=139 38007: (5000-z)=9

3×х-7800=1200
3×х=7800+1200
3×х=9000
х=9000:3
х=3000

(у+2958):57=139
у+2958=57×139
у+2958=7923
у=7923-2958
у=4965

38007:(5000-z)=9
5000-z=38007:9
5000-z=4223
z=5000-4223
z=777