A) -21 (8) = -10101 (2), 158 (10) = 10011110 (2)
10011110
-00010101
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10001001 = 2^7 + 2^3 + 2^0 = 128+8+1 = 137
б) -149 (8) = -10010101 (2), 36 (10) = 100100 (2)
10010101
-00100100
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-01110001 = -(2^6 + 2^5 + 2^4 + 1 )= -(64+32+16+1) = -113