gmatt1476 wrote:
3P5
+4QR
_____
8S4
In the correctly worked addition problem shown, P, Q, R, and S are digits. If Q = 2P, which of the following could be the value of S ?
(A) 3
(B) 2
(C) 1
(D) -1
(E)-2
PS07601.02
R must be 9 because the units digit of the sum, 5 + R, is 4.
3P5 + 4Q9 = 8S4
305 + 10P +409 + 10Q = 804 +10S
Since Q = 2P,
714 + 30P = 804 + 10S
30P - 90 = 10S
3P - 9 = S
S = 3(P - 3)
We can see that S must be divisible by 3, and there is only one answer choice divisible by 3.
Answer: A
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