15. If the tens digit x and the units digit y of a positive integer n are reversed, the resulting integer is 9 more than n. What is y in terms of x ?
(A) 10 - x
(B) 9 - x
(C) x + 9
(D) x - 1
(E) x + 1
Hi,
I though the answer is D) but turned out to be E). Can anyone explain why??
500 ps test23 #15
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- jayhawk2001
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n can be written as 10x + ydunkin77 wrote:15. If the tens digit x and the units digit y of a positive integer n are reversed, the resulting integer is 9 more than n. What is y in terms of x ?
(A) 10 - x
(B) 9 - x
(C) x + 9
(D) x - 1
(E) x + 1
Hi,
I though the answer is D) but turned out to be E). Can anyone explain why??
If we reverse x and y, we get a number of the form 10y + x
10y + x = 9 + 10x + y
9y = 9x + 9
y = x + 1
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