Answer:
2
Explanation:
Only 1/5 of Miss Williams' class has a cell phone, so we work this out by dividing the number of students by 5
20÷5=4
Out of this group of 4 students, only 1/2 are allowed to use social media
4÷2=2
This means that only 2 pupils have a phone and are allowed to use social media at the same time.
If you need to express this in fraction form, it would be 1/10 of the class