Actually Welcome to the Concept of the linear equation in two variables.
So we have to form two equations to solve this.
Let the number of children be 'x' and number of adults be 'y'.
hence, we get as,
x+y = 630 ..... (1)
and also, to their total cost spending, we get as,
1.5x + 2.25y = 1170 ...... (2)
solving (1) and (2) we get as,
Number of children were = 330
and Number of Adults were = 300
(Solved in the attachment)
