You can solve this by using two equations, each with two unknowns, or variables.
The variables are the number of cardholders tickets (C), and the number of non-cardholders tickets (N).
There were 305 tickets sold, so the total of cardholders plus noncardholders is 305:
N + C = 305
Each cardholders ticket costs 1.25, so the amount from sales of cardholders tickets is 1.25 * C.
Each non-cardholders ticket costs 2.50, so the amount from sales of non-cardholders tickets is 2.50 * N.
The total sales is 578.75:
1.25C + 2.5N = 578.75
You now have two equations in two unknowns. Now, change the first equation to express one of the variables in term of the other (by subtracting C from both sides of the equation:
N + C = 305
N = 305 - C
Now, use substitution to eliminate N from the second equation:
1.25C + 2.5N = 578.75
substitute for N:
1.25C + 2.5(305 - C) = 578.75
distributive property:
1.25C + (2.5 * 305 - 2.5 * C) = 578.75
perform multiplication inside the parentheses
1.25C + (762.5 - 2.5C) = 578.75
eliminate the parentheses
1.25C - 2.5C + 762.5 = 578.75
combine variable terms
-1.25C + 762.5 = 578.75
subtract 762.5 from both sides of the equation
-1.25C = -183.75
divide both sides by -1.25
C = 147
Now that you know how many cardholder tickets were sold, use the original equation to determine the non-cardholder tickets:
N + C = 305
substitute for C:
N + 147= 305
subtract 147 from both sides of the equation:
N = 305 - 147
N = 158
C = 147, N = 158
There were 147 cardholder tickets sold, and 158 non-cardholder tickets sold. Double check by plugging those values into the second equation:
1.25C + 2.5N = 578.75
1.25 * 147 + 2.5 * 158 = 578.75
183.75 + 395 = 578.75
578.75 = 578.75
KEVIN B.
11/10/13