5 years ago, Ebo was 3 times as old as Atu. In 3 years, Ebo will be twice as old as Atu. What is the sum of their ages now?
A) 18
B) 24
C) 28
D) 35
E) 42
An alternate approach is to TEST CASES.
5 years ago, Ebo was 3 times as old as Atu.
What is the sum of their ages now?
Case 1: Five years ago A=1 and E = 3*1 = 3
Sum of the their ages now = (1+5) + (3+5) = 14.
14 is not among the answer choices.
Case 2: Five years ago A=2 and E = 3*2 = 6
Sum of the their ages now = (2+5) + (6+5) = 18.
In 3 years, A = 7+3 = 10 and E = 11+3 = 14.
Since Ebo is not twice as old as Atu, eliminate A.
Case 3: Five years ago A=3 and E = 3*3 = 9
Sum of the their ages now = (3+5) + (9+5) = 22.
22 is not among the answer choices.
Notice the PATTERN:
The resulting sums -- 14, 18, 22 -- keep increasing by 4.
Thus, the correct sum must be in the following list:
14, 18, 22, 26, 30, 34, 38,
42...
Only the value in red is among the remaining answer choices.
The correct answer is
E.
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