Answer:
We have a total of 7200 plants.
The plants are distributed in one field with 18 rows of 200 plants and another field with 9 rows of N plants.
Where we want to find the value of N.
The total number of plants in the rows is:
"number of rows times number of plants in each row."
Then the total number of plants is:
18*200 + 9*N
And we know that we have a total of 7200 plants, then:
18*200 + 9*N = 7200
9*N = 7200 - 18*200 = 3600
N = 3600/9 = 400
Then the plants are distributed in 18 rows of 200 plants for one field, and 9 rows of 400 plants in the other field.