Answer:
The price for a child and adult ticket is $16.5
Explanation:
Let a represent the price for an adult ticket and c the price for a child ticket
a + 2c = 21 ------- equation (1)
The cost of the children's ticket is 2c
a = 3 + 2c ------- equation (2)
Substitute the value of a in equation (2) into equation (1)
a + 2c = 21
3 + 2c + 2c = 21
4c = 21 - 3
4c = 18
c = 18/4 = 4.5
The price for a child ticket = $4.5
Substitute the value of c into equation 2
a = 3 + 2c
a = 3 + 2(4.5) = 3 + 9 = 12
The price for an adult ticket is $12
Price for a child and adult = $4.5 + $12 = $16.5