21. Transportation A youth group with 26 members is going skiing. Each of the five chaperones will drive a van or sedan. The vans can seat seven people, and the
sedans can seat five people. Assuming there are no empty seats, how many of each
type of vehicle could transport all 31 people to the ski area in one trip?

The number of vans used is three and the number of sedans is two

Let :

v represent the number of vans

s represent the number of sedans

The following equations can be gotten

7v + 5s = 31 equation 1

v + s = 5 equation 2

The elimination method would be used to solve for v and s

Multiply equation 2 by 7

7v + 7s = 35 equation 3

Subtract equation 1 from 3

2s = 4

s = 4/2

s = 2

Substitute for s in equation 2

v + 2 = 5

v = 5 - 2

v = 3

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Answers:

2 sedans and 3 vans

Work Shown:

s = number of sedans

v = number of vans

1 sedan = 5 seats

s sedans = 5s seats

1 van = 7 seats

v vans = 7v seats

5s+7v = all seats

5s+7v = 31

Let's go through all the values of s to see which values of v work.

As a check:

2 sedans = 5*2 = 10 seats

3 vans = 7*3 = 21 seats

10+21 = 31 seats total

This confirms the answer.