A gardener plants his garden with 5550 trees and arranged them so that there is one plant more per row as there are rows then number of trees in a row is:

Let there be n rows, then number of trees in each row = (n + 1)
Thus, total number of trees,
n × (n +1) = 5550
Now, at this moment this problem can be solved in two ways. First by finding the roots of quadratic equation. Second, by using the values from options.
74 × 75 = 5550
i.e. (n + 1) = 75