Answer:
The number of visitor 18 years or younger than 18 years is 42 .
Explanation:
Given as :
The total number visitor in the museum = 224
The price of admission for visitor older than 18 years = $ 12
The price of admission for visitor 18 years or younger than 18 years = $ 8
The total price of tickets = $ 2,520
Let The number of visitor older than 18 years = x
And The number of visitor 18 years or younger than 18 years = y
Now, According to question
The total number visitor in the museum = 224
Or, The number of visitor older than 18 years + The number of visitor 18 years or younger than 18 years = 224
Or, x + y = 224
And $ 12 x + $ 8 y = $ 2,520 ..........A
Or, $ 12 × ( x + y ) = $ 12 × 224
Or, $ 12 x + $ 12 y = $ 2688 ..........B
Solving Eq A and B
Or, ( $ 12 x + $ 12 y ) - ( $ 12 x + $ 8 y ) = $ 2688 - $ 2520
Or, ( $ 12 x - $ 12 x ) + ( $ 12 y - $ 8 y ) = $ 168
Or, 0 + 4 y = 168
∴ y =

I.e y = 42
So, The number of visitor 18 years or younger than 18 years = y = 42
And ∵ x + y = 224
I,e x = 224 - y
or, x = 224 - 42
∴ x = 182
So, The number of visitor older than 18 years = x = 182
Hence The number of visitor 18 years or younger than 18 years is 42 . Answer