Question

Mrs. Pregnals's biology classes are going on a field trip. She has them break into groups of three or four

students in order to do labs. She has a total of 120 students and 32 total groups are formed.
If i represents the number of three person groups and represents the number of four person groups, then
write a system of equations that models this situation.

Answer 1

x + y = 32 (1)

3x + 4y = 120 (2)

x = 8; y = 24

Explanation:

Total students = 120

Number of groups = 32

If the number of three person groups = x

Number of four person groups = y

write a system of equations that models this situation

x + y = 32 (1)

3x + 4y = 120 (2)

From (1)

x = 32 - y

Substitute x = 32 - y into (2)

3(32 - y) + 4y = 120

96 - 3y + 4y = 120

- 3y + 4y = 120 - 96

y = 24

Substitute y = 24 into (1)

x + y = 32

x + 24 = 32

x = 32 - 24

x = 8

x = 8; y = 24