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
n=10x+y and n'=10y+x --> n'-n=(10y+x)-(10x+y)=9 --> y=x+1.
Can anybody clear this for me
suppose I take first number as 10y + x and reverse it to get 10x + y
Then according to the equation (10x + y) - (10y + x ) = 9
9x -9y= 9
so why are we getting two different answers.
if I take first number to be 10x + y and reverse it to get 10y +x
then (10y + x) - (10x +y)= 9y- 9x=9
why two different answers ?
You cannot arbitrary assign which will be the "first" number and which will be the "second", since the stem explicitly clears that.
Positive integer n
has the tens digit x and the units digit y, so n=10x+y
Reversed integer, say n'
, has the tens digit y and the units digit x, so n'=10y+x
We are also told that " the resulting integer (so n'
) is 9 more than n
", which means n'-n=(10y+x)-(10x+y)=9
Hope it's clear.
Its clear now , great. Thank you