2. Out of 25 students, four received a grade of 5, five received a grade of 4, and five received a grade of 2. How many students received a grade of 1 and how many students received a grade of 3, if the average grade was exactly 3? Write down the answer.
2. Write the equation $\frac{4 \cdot 5+5 \cdot 4+2 \cdot 5+x+3 y}{25}=3$ ..... 1 point
$x+y=11$ ..... 1 point
Solving the system - procedure ..... 1 point
Solutions: $x=4$ ..... 1 point
$y=7$ ..... 1 point
Answer: 7 students received a grade of 3, and 4 students received a grade of 1. ..... 1 point