Let C represent children and let A represent adult tickets
Family 1 : 2A + 3C = 20
Family 2: A + 4C = 15
Let's solve the equation simultaneously:
2A + 3C = 20......................(1)
A + 4C = 15.......................(2)
From equation 2, make A the subject:
A = 15 - 4C
Now substitute (15 - 4C) for A in equation 1:
![2(15-4C)\text{ + 3C = 20}](https://img.qammunity.org/2023/formulas/mathematics/college/rhvnopan5una6e5ag7aaj4vkv888ye8z0u.png)
![30\text{ - 8C + 3C = 20}](https://img.qammunity.org/2023/formulas/mathematics/college/jsz0vp7y5i561zc5oh43qa4lb9rr1xgbdo.png)
![30\text{ - 5C = 20}](https://img.qammunity.org/2023/formulas/mathematics/college/25zaaum3k8jh1hm44v2t0gkvx5omc6cbvh.png)
Now we have:
![5C\text{ = 30 - 20}](https://img.qammunity.org/2023/formulas/mathematics/college/snibx59tv7yg5aiqeirajayak8l2xnvxuo.png)
![5C\text{ = 10}](https://img.qammunity.org/2023/formulas/mathematics/college/46v0u22ihtq8pzqa0mux01v1k89fx8wwn7.png)
To find C, divide both sides by 5:
![(5C)/(5)\text{ = }(10)/(5)](https://img.qammunity.org/2023/formulas/mathematics/college/dg5mw6ltjtlc9sm37rbnmfcgvdde7hq8f2.png)
![C\text{ = 2}](https://img.qammunity.org/2023/formulas/mathematics/college/o75tw701gqj7u6c3fgm4q262zt58a33r5z.png)
Now substitue 2 for C in equation 2:
A + 4(2) = 15
A + 8 = 15
subtract * from both sides:
A + 8 -8 = 15 -8
![A\text{ = 7}](https://img.qammunity.org/2023/formulas/mathematics/college/7ev87l3cid7j8jycko7quy22ljfmiry6i1.png)
Therefore, the cost of adult ticket is 7 pounds and the cost of children ticket is 2 pounds