Suppose the students who scored 85 and 90 on the math test take the test again and score 95 how manu stars would you have to add to the picture graph next to 95
key each star equals 4
math test scores
100 / // / / 20 people scored 100
95 / / / 12 people scored 95
90 / / / | 14 people scored 90
85/ 4 people scored 85

In this question, each star equal to 4 students. If the people on 85 and 90 take the test again that means their number should be 14+4 people= 18 people. 
If they all get 95, then it means we need to add 18 people to the 95 graph. The number of stars would be: 18 people / (4people/stars)= 4.5 stars

If you add the stars graph it will be easier. It should be clear that 85 will have 1 stars and 90 have 3.5 stars. Adding them up will be 1 stars + 3.5 stars= 4.5 stars