An ecologist is studying the distribution of dandelion plants in a school's green spaces. The diagram below shows a plan of the school grounds containing a triangular wildflower area adjacent to the school building. 
The ecologist counts all the dandelion plants growing within the wildflower area. They count a total of 45 dandelion plants. Calculate the density of dandelion plants in the wildflower area in plants per square metre (plants/m2\text{plants/m}^2plants/m2). Use the formula: area of a triangle=12×base×height\text{area of a triangle} = \frac{1}{2} \times \text{base} \times \text{height}area of a triangle=21×base×height