Question

Item 18 You and your friend are selling tickets to a charity event. You sell 7 adult tickets and 16 student tickets for $120. Your friend sells 13 adult tickets and 9 student tickets for $140. What is the cost of a student ticket?

Answer 1

$4

You can get this by setting up 2 equations. One for you and one for your friend. Each should have a cost equation. Let x = adult and y = student.

You: 7x + 16y = 120
Friend: 13x + 9 = 140

Solve using any method. 

Answer 2

Answer:

The cost of student ticket is $4

Step-by-step explanation:

let

price for an adult = a

price for a student = b

7a + 16b = 120...........(i)

13a + 9b = 140............(ii)

make a subject of the formula in equation(i)

7a = 120 - 16b

divide through by 7

a = 120/7 - 16/7b

insert a in equation(ii)

13(120/7 - 16b/7)  + 9b = 140

1560 /7 - 208b/7 + 9b = 140

collect like terms

(-208b + 63b)/7 = 140 - 1560/7

-145b/7 =(980 - 1560) /7

-145b/7 = -580/7

multiply both sides by 7

-145b = -580

divide both sides by -145

b = -580/-145

b = 4

Insert the value of b in equation(ii)

13a + 9b = 140............(ii)

13a + 9(4) = 140

13a + 36 = 140

13a = 140 - 36

13a = 104

divide both sides by 13

a = 104/13

a = 8

The cost of student ticket is $4