1)
134+x=426+583
134+x=1009
x=1009-134
x=875
2)
208+x=137+416
208+x=553
x=553-208
x=345
3)
x-506=429-215
x-506=214
x=214+506
x=720
4)
y-164=500-308
y-164=192
y=192+164
y=356
5)
942-a=254+126
942-a=380
a=942-380
a=562
6)
801-b=368+224
801-b=592
b=801-592
b=209
===========
39+x=78+84
39+x=162
x=162-39
x=123