Ответ: \eta= \cfrac{T_H-T_X}{T_H} T_H=4T_X
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T_X=0.25T_H\eta= \cfrac{T_H-0.25T_H}{T_H} = \cfrac{0.75T_H}{T_H} =0.75=75\% Ответ: 0,75 или 75%