The trapezoidal lot has four sides measuring 10 meters, 15 meters, 35 meters, and 40 meters. To plant santan plants all around the lot, we first need to find its perimeter by adding all the side lengths. The total perimeter is 100 meters. This means santan plants will be planted along a distance of 100 meters around the lot. If you plant one santan per meter, you will need 100 santan plants.