espy

x-10=20*2                2x+20=20                  10x=10

x-10=40                    2x=0                           x=1

x=50                          x=0

dskryto (х-10)/2=20
х-10=40
х=30

(х+10)*2=20
2х+20=20
2х=0
х=0

х*10-2=8
10х=10
х=1

х/10+2=8
х/10=6
х=0.6