Problem 3. Each student's mentor gave them 2 apples, and 19 apples remained in the basket. How many students and how many apples are there, if their total sum is 100?
Solution. If the number of students is denoted by $x$, then the basket will contain $2 x+19$ apples. From the condition that the total number of students and apples is 100, we get $x+2 x+19=100$. By solving the equation, we find that there are 27 students and 73 apples.