90% of students at a university use a backpack, while the rest do not. Of all the students, 50% carry their laptops with them and 5% carry neither a backpack nor laptop. What percentage of students carry their laptops and use a backpack?

Answer 1

this would be VERY easy with a Venn diagram

looking at 100 students
... 90 use a backpack
... 50 carry a laptop
... 5 do neither

let b equal the number who do both

(90 - b) + (50 - b) + b = 100 - 5