748 - (b + 248) = 211
Ответ:
748 - b - 248 = 211
748 - 248 - b = 211
500 - b = 211
b = 500 - 211
b = 289
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748 - (289 + 248) = 211
211 = 211
b + 248 = 748 - 211 b + 248 = 537 b = 537 - 248 b = 289 можно проще:)