So, there is a rectangular park with longer side (length) 150 yards and shorter side (width) 125 yards.
so walking around the rectangular park once is like covering the Perimeter (p) of the rectangular park.
So, lets find the perimeter of the park. Perimeter of rectangle = 2 ( l + w) = 2 ( 150 + 125 ) = 2 * 275 = 550 yards
Now, walking around the park two times is like doubling the Perimeter of the rectangle. So, when Debbie walks around the park 2 times, he covers the perimeter of the rectangular field twice.
Now, If Debbie wanted to walk 1,000,000 yards, she has to walk the rectangular park (1,000,000 / the Perimeter of the park) i.e. 1,000,000 / 550 = 1818.18 times
So, (a) she walks 1100 yards (b) She have to walk 1818.18 times
For the answer to the question above, it is -18% because to find rate we subtract the rate, in this case, is .82 or 82% - 1 or 100% and that would give you the rate, in this case, its decreasing by an 18%