Hello!
The answer is:

Why?
From the statement we know that he planted peas in 3/8 of her garden and herbs in 1/8 of it, it means 1/2 of the garden, and after that, she divided the rest of the garden into 6 sections. We are asked to find the fraction of the original garden is each section, so:
Calculations:
For Planted garden

So, she planted 1/2 of the garden, it means that there is another 1/2 free to be divided into 6 sections,
Then,

Therefore,
Each section would be
of the original garden.
Have a nice day!