C = # of children and charged $3.50 each
A = # of adults and charged $9.00 each
($3.5 x C)+ ($9.0 x A) = $1505
(this represents the total amount of money collected)
A + C = 210 (total number of people who got in)
So now you have two equations and two unknowns - so you can solve it via substitution.
A = 210 - C
Put this term for C into the other equation
3.5*C + 9*(210-C) = 1505
3.5C + 1,890 - 9C = 1505
385 = 5.5C
C = 385/5.5
C = 70 Children
A = 210 - 70
A = 140 Adults
Find the graph where the lines intersect at those two numbers
