Tính P

$$\begin{gathered} cho x,y,z,t thỏa mãn:\frac{x}{y+z+t}=\frac{y}{z+t+x}=\frac{z}{t+x+y}=\frac{t}{x+y+z} \\ tính P = {\left(\frac{x+y}{z+t}\right)}^{2017} + {\left(\frac{y+z}{x+t}\right)}^{2018}+{\left(\frac{z+t}{x+y}\right)}^{2019}+{\left(\frac{t+x}{z+y}\right)}^{2020} \end{gathered}$$