Tanya has a garden with a trench around it. The garden is a rectangle with length 2 \dfrac12 \text{m}2
2
1
m2, start fraction, 1, divided by, 2, end fraction, start text, m, end text and width 2 \text{ m}2 m2, start text, space, m, end text. The trench and garden together make a rectangle with length 3 \dfrac12 \text{m}3
2
1
m3, start fraction, 1, divided by, 2, end fraction, start text, m, end text and width 3 \text{ m}3 m3, start text, space, m, end text.
Find the area of just the trench.