Here's how to calculate the capacity of Matti's greenhouse. First, we need to know the dimensions: the base width and length are 7 feet by 15 feet, and the height of the prism is 7 feet. To find the capacity of the greenhouse, we need to calculate the volume of the rectangular base, which is a triangular prism. We can do this by multiplying the area of the triangular base by the height. Therefore, the capacity of Matti's greenhouse is [(1/2)(7)(7)][15] which equals [(1/2)(49)][15], which equals [(24.5)][15], resulting in a capacity of 367.5 cubic feet.