please help with reversed digits problem
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
What am I doing wrong?
y(x-x) = 9 ??? undefined!
Desperately wanting 700+
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Trying to make mom and pop proud
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Let xy=23 then on reversing the digits 32=23+9
Now x=2 and y=3 let us substitute the values of x in each of the answer choices and see which one gives us the value of y as 3.
A 10-x----10-2=8 but y is not 8 so A is out
B 9-x-----9-2=7 but y is not 7 so B is out
C x+9------2+9=11 definitely out
D x-1----------2-1=1 but y is not 1 and so D is out
E x+1--------2+1=3 and the value of y is 3.Hence,E is the answer
its easy to solve this kind of problems by equations
original number N=10X +Y
After reversing the number becomes 10Y + X
Now 10Y+X happens to be 9 greater than the original number N
or x =y+1
Answer should be D
Answer is E.
xy=n which means 10x+y=n
Now when you flip them it will be
yx=n+9 meaning 10y+x=n+9
Solve them and you'll get x+1
10x +y is n
10y+x = 10x + y + 9
9x -9y + 9=0
9 ( x-y+1) =0
x-y +1 =0
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