Ответ:

1.(х-18,2) +0, 39=4, 7

(х-18 ,2) =0, 39-4, 7

(х-18,2) =4, 31

х=18,2+4, 31

х=22, 51

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2. 74,6-(t-0, 34) =31

( t-0, 34) =74, 6+31

(t-0, 34)=105, 6

t=105, 6-0, 34

t =105, 26

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