$P \times 1.4 \times (1 - \frac{2x}{100}) = P$ $1.4 \times (1 - 0.02x) = 1$ $1 - 0.02x = \frac{1}{1.4} \approx 0.7143$ $0.02x = 0.2857 \Rightarrow x \approx 14.285$