a)(x+27)-12=42
б)115-(35+у)=39
в)z-35-64=16
г)28-t+35=53

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а) (х+27)-12 = 42х = 42-27х = 15х = 15+12х = 27 ________Ответ: 27б) 115-(35+у) = 39у = 35+39у = 74у = 115-74у = 41_______Ответ: 41в) z -35-64 = 16 z = 64+35z = 99z = 99+16z = 115________Ответ: 115г) 28-t+35 = 53t = 53-35t = 18t = 28-18t = 10_________Oтвет: 10