Inactive Tutor answered 12/07/14
Tutor
New to Wyzant
A = number of $5 tickets sold
B = number of $10 tickets sold
C = number of $15 tickets sold
The total number of tickets sold gives us equation 1.
A + B + C = 180
The total amount of money collected gives us equation 2.
5A +10B + 15C = 1900
The relationship between the number of each type of ticket sold gives us equation 3.
A + C = 2B
Substitute equation 3 into equation 1 as follows:
rewrite A + B + C = 180 as A + C + B = 180. Since we know what A + C is from equation 3, substitute and get:
2B + B = 180
3B = 180
B = 60
Now, substitute the value of B in equations 2 and 3
5A + 10(60) + 15C = 1900 equation 2
A + C = 2(60)
Rewrite
5A + 15C = 1300 (new equation 2)
A + C = 120 (new equation 3)
Using elimination, solve:
5A + 15C = 1300
-5A -5C = -600
Add these 2 equations together to get
10C = 700
Therefore C = 70
Substitute C back into one of your equations (say equation 3) to get
A + 70 = 120
A = 50
A=50, B=60, C=70