5

Set 6: Systems of Equations (Advanced)

Explanation

Answer: C

Anna is 3 times as old as her daughter. The sum of their ages is 48. How old is Anna?

A.

30 years old

B.

33 years old

C.

36 years old

✓ Correct
D.

39 years old

Detailed Explanation

Choice C is correct. Choice C is the correct answer. Let AA = Anna's age and DD = daughter's age. System: {A=3DA+D=48\begin{cases} A = 3 D \\ A + D = 48 \end{cases} Step 1: Substitute: $$$3D + D = 484D = 48$D = 12 Step 2: Find A: A=3(12)=36A = 3(12) = 36 Solution: Anna is 36 years old Verification: 36+12=4836+ 12 = 48 ✓ and 36=3(12)36= 3(12) ✓ Strategic Tip: "Times as old" translates to multiplication.

Key Steps:

The correct answer is 36 years old

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