According to the information given in the exercise, the following expression represents the area of the rectangular garden:
[tex]6\mleft(6.5x+2.5\mright)[/tex]And the following expression represents the combined area of the walkway around the rectangular garden and the area of the garden:
[tex]6.5\mleft(8x+6\mright)[/tex]You can identify that the word "combined" indicates that that expression was obtained by adding both areas.
Knowing the above, you can set up the following equation:
[tex]6(6.5x+2.5)+A=6.5(8x+6)[/tex]Where "A" is the area of the walkway around the rectangular garden.
Solving for "A", you get the following expression:
[tex]\begin{gathered} A=6.5(8x+6)-6(6.5x+2.5) \\ A=52x+39-39x-15 \\ A=13x+24 \end{gathered}[/tex]The answer is:
[tex]13x+24[/tex]