
Christine L. answered 03/04/15
Tutor
4.9
(354)
HS Math Teacher and HS/College Tutor specializing in Math & Test Prep
I am only dealing with part of your question in my answer. I will be addressing how to solve for the portion that has already been sold.
Let a = number of adult tickets
Let c = number of child tickets
Step 1: Figure out what equations represent your situation.
Dealing with quantity of tickets:
a + c = 548
Dealing with revenue:
5a + 2.5c = 2460
Step 2: Create a system of equations
Line1: a + c = 548
Line 2: 5a + 2.5c = 2460
Step 3: Divide "5a + 2.5c = 2460" by "5" all the way across in order to get "a" with a coefficent of 1
Line 2: (5a/5) + (2.5c/5) = (2460/5)
Line 2: a + 0.5c = 492
Step 4. Put this new Line 2 back into your system of equations.
Line 1: a + c = 548
Line 2: a + 0.5c = 492
Step 5: Subtract Line 2 from Line 1. One way to do this is to distribute a negative to all terms on one line and then add them together. Use whatever works for you
Line 1: a + c =548
Line 2: -a -0.5c = -492
Simplify: 0 + 0.5c = 56
Step 6: Solve for "c".
c = (56/0.5) --> c = 112
Step 7. Plug c = 112 back into Line 1 to solve for a
a + 112 = 548 --> a = 548 - 112 --> a = 436
Step 8. Double check your work
a + c = 548
436 + 112 = 548 (Yay!)
5a + 2.5c = 2460
5(436) + 2.5(112) --> 2180 + 280 = 2460 (Yay!)
Therefore, you know a = 436 and c = 112, meaning that you sold 436 Adult tickets and 112 Child tickets.