total enrollments per classs

Question

There are two times as many people in the Psychology class as in History. There are 15 More people in the Algebra class then in History. The total of the three classes is 63. How many are enrolled in each class?

Answer 1

p = psychology students

h = history students

a = algebra students

 

p = 2h

a = h + 15

p + a + h = 63

 

Using substituion

(2h) + (h+15) + h = 63

4h + 15 = 63

4h = 48

h = 12

 

There are 12 students in history

p = 2h = 24 students in psychology

a = h+15 = 27 students in algebra

 

Check: p+h+a = 63

          24+12+27 = 63

          63 = 63