Answer:
25 students take both subjects.
Explanation:
Solve for 60% of 300 students:
60/100 = x/300
Cross multiply:
60 × 300 = 100 × x
18000 = 100x
Divide both sides by 100:
180 = x
Solve for 20% of 300 students:
20/100 = x/300
20 × 300 = 100 × x
6000 = 100x
60 = x
Solve for the percentage of students in chemistry:
x/100 = 35/300
x × 300 = 100 × 35
300x = 3500
x = 11.66666...7
x = about 11.7%
Find the difference in percentages:
100 - 60 - 20 - 11.7
8.3
8.3% take both subjects
Solve for 8.3% of students:
8.3/100 = x/300
8.3 × 300 = 100 × x
2490 = 100x
24.9
About 25 students
Check your work by adding all the students together (to get to 300):
25 + 60 + 180 + 35
300 students total
This is correct!