Х-30=50,х+49=50,100-х=50,70-х=50,20+х=50,51-х=50,0*4+х=50,2*5+х=50

Х-30=50
х=50+30
х=80
х+49=50
х=50-49
х=1
100-х=50
х=100-50
х=50
70-х=50
х=70-50
х=20
20+х=50
х=50-20
х=30
51-х=50
х=51-50
х=1
0*4+х=50
(0*4=0)
х=50-0
х=50
2*5+х=50
(2*5=10)
х=50-10
х=40

Х-30=50,   
Х=5030,
Х=80.
Х+49=50,
Х=50-49,
Х=1.
100-Х=50,
Х=100-50,
Х=50.
70-Х=50,
Х=70-50,
Х=20.
20+Х=50,
Х=50-20,
Х=30.
51-Х=50,
Х=51-50,
Х=1.
0×4+Х=50,
0+Х=50,
Х=50-0,
Х=50.
2×5+Х=50,
10+Х=50,
Х=50-10,
Х=40.