First, write the two equations letting c=children and a=adults :
c+a=2200
1.50(c) + 4.00 (a)=5050
Step-by-step explanation:
Now, use substitution ...
c=2200−a
1.50(2200−a)+4.00(a)=5050
Simplify ...
2.5a=1750
a=700
Using the first equation ...
c=2200−a=2200−700=1500
In summary, there were 700 adults and 1500 children .
hope that helped