1. х+70480=120000
х=120000-70480
х=49520
49520+70480=120000
120000=120000
2. 30600-у=1900
у=30600-1900
у=28700
30600-28700=1900
1900=1900
3. 240700-u=180950
u=240700-180950
u=59750
240700-59750=180950
180950=180950
4. z-49430=87960
z=87960+49430
z=137390
137390-49430=87960
87960=87960