There are a total of 189 students in the school.
Explanation:
Let the total no. of students in the school be 'y'.
There are 42 students in sixth grade.
The fraction of students in sixth grade to the total students is (2/9)
That is, 2/9 of the total students in the school are in sixth grade.
(2/9) y = 42
y = 42(9) /2
y = 189
There are a total of 189 students in the school.