Answer:
Children=21 Adult=35
Step-by-step explanation:
[using c for children tickets and a for adult tickets]
56=c+a and 203=3c+4a [starting system of equations]
a=56-c ---> 203=3c+4(56-c) [plugging the first eq. into the second]
203=3c+224-4c [simplify]
-21=-c [simplify 2.0]
c=21 [simplify 3.0]
56=21+a [plugging back into org. eq.]
so a=35
