There is a man who plotted a land in shape of a trapezium with its parallel sides to be 15m and 5m & height=9m.

The Panchayat decided to take a triangular plot of land from one side to construct a school. He reluctantly agrees to this.
is this can be possible? Which are the possible triangular plots that can be taken by the Gram Panchayat?
and What value of the rich man can be seen here?

also, find area of parallelogram