How to write the solution to the third question? Solve the equation and then learn to solve it.

The total area of parallelogram is 30×20=600 square meters, and the transverse path area is 30× 1=30 square meters. The vertical path area is 20× 1=20 square meters. There is an overlapping area of 1× 1= 1 m2 in the middle. So the grassland area is 600-30-20+ 1=55 1 square meter.