45+x=97
х = 97 - 45
х = 52
500=200+x
х = 500 - 200
х = 300
a+230=400
а = 400 - 230
а = 170
x+39=390
х = 390 - 39
х = 351
45+x=97
х = 97 - 45
х = 52
500=200+x
х = 500 - 200
х = 300
a+230=400
а = 400 - 230
а = 170
x+39=390
х = 390 - 39
х = 351