Let x and y be the number of strands used to decorate a bush and a tree, respectively. Therefore, the system of equations is
[tex]\begin{cases}4x+2y=34 \\ 4x+4y=52\end{cases}[/tex]
To solve the system using the elimination method, subtract the first equation from the second one; then,
[tex]\begin{gathered} (4x+4y)-(4x+2y)=52-34 \\ \Rightarrow2y=18 \\ \Rightarrow y=9 \end{gathered}[/tex]
Substitute the last result into the second equation,
[tex]\begin{gathered} y=9 \\ \Rightarrow4x+4y=4x+4\cdot9=4x+36 \\ \Rightarrow4x+36=52 \\ \Rightarrow4x=16 \\ \Rightarrow x=4 \end{gathered}[/tex]
Thus, to decorate every bush, we need 4 strands of lights, and for every tree 9 strands of lights