Question 1026807
This analysis is done strictly in symbols.


w for width of the garden, L for the length of the garden.  The uniform width of the walkway around the garden is u.


Area of the garden, {{{wL}}}
Area of the walkway AND garden together, {{{(w+2u)(L+2u)}}}


Area of the combined walkway & garden MINUS area of just the garden IS the area of just the walkway.
{{{highlight((w+2u)(L+2u)-wL)}}}------which you should find is simplifiable.