Answer:
There are 71 students that are left
Step-by-step explanation:
Let's calculate the number of students left this way:
Total students = 30 * 6 = 180
Students that went to the the slides = 42
Students that went to the the swings = 28
Students that went to the the swings = 39
Students left = Total students - Students that went to the the slides - Students that went to the the swings - Students that went to the the swings
Replacing with the real values, we have:
Students left = 180 - 42 - 28 - 39
Students left = 180 - 109
Students left = 71