9. Amateur Dima and professional Fedya both chopped wood and boasted to each other about how much they had chopped. In doing so, Dima exaggerated the result of his work by 2 times, Fedya by 7 times, and in total, it turned out to be three times more wood than in reality. Who chopped more wood and by how many times?

(D. Shiryayev)
9. Answer: Dima chopped 4 times more wood than Fedya. If Dima chopped $D$ wood, and Fedya chopped $F$ wood, then from the condition, it is easy to form the equation: $2 D+7 F=3(D+F)$. From this, we immediately get $D=4 F$.