1) х + 985 = 1020
х = 1020 - 985
х = 35
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35 + 985 = 1020
1020 = 1020
2) х + 18 = 28 + 32
х + 18 = 60
х = 60 - 18
х = 42
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42 + 18 = 28 + 32
60 = 60
3) х + 78 + 23 = 134
х + 101 = 134
х = 134 - 101
х = 33
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33 + 78 + 23 = 134
134 = 134