Answer:
1/10
Explanation:
First, let's find the total number of students (25+15+5+5). We don't need to worry about them overlapping, as the questions says "only." We get the total of 50.
Out of the 50 students, there are 5 students that play both instruments. This means that 5 is our numerator and 50 is our denominator, giving us 5/50 or 1/10.