Answer:
The area of a trench is 5.5 m² .
Step-by-step explanation:
Formula
Area of a rectangle = Length × Breadth
As given
Tanya has a garden with a trench around it.

i.e

Put in the above formula

= 5 m²
As given

i.e



= 10.5 m²
Area of the trench = Area of garden with trench - Area of garden
Put the value in the above
Area of the trench = 10.5 m² - 5 m²
= 5.5 m ²
Therefore the area of a trench is 5.5 m² .