Answer :
The shape of the garden is in the form of a right angled triangle. The area of the garden therefore is given as;
[tex]\begin{gathered} \text{Area}=\frac{1}{2}bh \\ b=\text{base (5)} \\ h=\text{vertical height (12)} \\ \text{Therefore,} \\ A=\frac{1}{2}\times5\times12 \\ A=30 \\ \text{The area of Jessica's garden is 30 square yards.} \\ \text{She intends to plant 3 plants for each square yard.} \\ \text{The total number of plants therefore would be derived as,} \\ \text{Plants}=\text{Total area x 3} \\ \text{Plants}=30\times3 \\ \text{Plants}=90 \end{gathered}[/tex]Jessica would be having 90 plants in her garden.
This is because she came up with 30 square yards as the area of her garden, and she would be planting 3 plants in each square yard.