7

Set 3: Systems of Equations (Advanced)

Explanation

Answer: A

A theater sold 300 tickets for a play. Adult tickets cost $12 and student tickets cost $8. Total revenue was $2,800. How many adult tickets were sold?

A.

100 adult tickets

✓ Correct
B.

150 adult tickets

C.

125 adult tickets

D.

175 adult tickets

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Let aa = adult tickets and ss = student tickets. Step 1: Set up the system: {a+s=30012a+8s=2800\begin{cases} a + s = 300 \\ 12 a + 8 s = 2800 \end{cases} Step 2: From first equation: s=300as = 300 - a Step 3: Substitute: $$$12a + 8(300 - a) = 280012a+24008a=280012a + 2400 - 8 a = 28004a = 400a = 100$$ Solution: 100 adult tickets (and 200 student tickets) Verification: $$100+ 200 = 300$$ ✓ and 12(100) + 8(200) = 1200 + 1600 = 2800StrategicTip:Revenueproblems:tickets×price=totalrevenue.ChoiceBisincorrectbecause✓ Strategic Tip: Revenue problems: tickets × price = total revenue. Choice B is incorrect because12(150) + 8(150) = 1800 + 1200 = 3000 \neq 2800.ChoiceCisincorrectbecause. Choice C is incorrect because 12(125) + 8(175) = 1500 + 1400 = 2900 \neq 2800.ChoiceDisincorrectbecause. Choice D is incorrect because 12(175) + 8(125) = 2100 + 1000 = 3100 \neq 2800$.

Key Steps:

The correct answer is 100 adult tickets

Why others are wrong:
B: Choice B is incorrect and may result from a calculation error.
C: Choice C is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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