44. If there were $x$ rows, then in each of them there were $(x-3)$ sixth graders. Since there were 3 fifth graders in each row, there were $x$ students in each row. Then the total number of students at the evening was $x \cdot x=x^{2}$. According to the condition $x^{2}>70$ and $x^{2}<90$. This condition is satisfied only by $x=9 ; 9^{2}=81$. Therefore, there were 9 rows, there were $54(6 \cdot 9=54)$ sixth graders, and there were $27(3 \cdot 9=$ $=27)$ fifth graders.
44. At a mathematics evening, there were students from grades V and VI. Together, they were more than 70 but less than 90. The total number of rows of chairs in which the students sat in the hall was 3 more than the number of sixth-graders in each row, and the fifth-graders sat 3 in each row. How many sixth-graders and fifth-graders were there separately?