You can
put this solution on YOUR website!It is a very simple problem.
Assume, tickets were sold to x children and y adults.
As the total number of tickets sold were 575, so

...(1)
The worth of tickets was $3575, so

... (2)
On Multiplying Eq(1) by 4 and subtracting from Eq(2):
So,
Now, from Eq(1) x = 150
So, there were 150 children and 425 adults.
You can
put this solution on YOUR website!questions like this...you need to investigate th eenglish and try to convert it to maths. There will be 2 things you do not know, so you need 2 (or more) equations to find them.
I have written Lessons on this site on Linear Equations and solving them simultaneously, so look at those to help you understand that bit...first the 2 equations:
1. Define the 2 things you are asked for:
Let x = number of child tickets
Let y = number of adult tickets.
2 Find the 2 equations:
a. we know the total number of tickets sold one night = 575, so x+y=575 --eqn1
b. each child ticket = $4:
if we sold 1, that would be 4*1
if we sold 2, that would be 4*2
if we sold 5, that would be 4*5
so, if we sold x, that would be a total cost of 4*x... or 4x
Similarly, for the adult tickets, their total cost = 7y
And we know that the total cost of all the tickets was $3575, so 4x+7y = 3575 --eqn2.
Now you have the 2 equations, look at my lessons to find out how to solve them.
Good luck.
jon.