Ravi can walk a certain distance in 40 days when he rests 9 hours a day. How long will he take to walk twice… · ABC26GN3617

Let the required number of days be $x$. More distance, More days required (Direct Proportion) More speed, Less days required (Indirect Proportion) More resting hours, More days required (Direct Proportion) Distance $$\left.\begin{array}{l} 1: 2 \\ 2: 1 \\ 9: 18 \end{array}\right\}:: 40: x \begin{aligned} & \therefore \quad 1 \times 2 \times 9 \times x= \\ & 2 \times 1 \times 18 \times 40 \Leftrightarrow x=\frac{2 \times 18 \times 40}{2 \times 9}=80 . \end{aligned}$$