# Питон 3
# -*- coding: utf-8 -*-
data = []
  
x = 30
y = 50
i = 'γ = x+y = '+str(x+y)
data.append(i)
i = 'ξ = x-y = '+str(x-y)
data.append(i)
# Запись в файл
with open('Отчёт.txt','w') as file:
#    print('\n'.join(map(str, data)), file=file)
#    data.decode('utf-8').encode('utf-8')
    print('\n'.join(map(str, data.decode('utf-8').encode('utf-8'))), file=file)

 with open("Отчёт.txt", "w", encoding="utf-8") as fail:
    fail.write('\n'.join(data))

 with open("Отчёт.txt", "w", encoding="utf-8") as file:
    file.write('\n'.join(data))