Bunuel
When positive integer x is divided by 9, the remainder is m and when positive integer y is divided by 9, the remainder is n. If m > n, what is the value of m + n ?
(1) x + y is a multiple of 9.
(2) x*y divided by 9, the remainder is 5
we know that x=9a+m and y=9b+n. And m>n.
Value of m and could be (0,1,2,3,4,5,6,7,8)
Taking statement 1.
We are given that
x + y is a multiple of 9.. And we know that x=9a+m and y=9b+n. Therefore x+y= 9a+m+9b+n. Since we know that
x+y is a multiple of 9. That means
m+n should be a multiply of 9. We can also conclude that value of m or n can be any value among (0,1,2,3,4,5,6,7,8). Given that m>n. m can never be 0. That means n has to be any value from (0,1,2,3,4,5,6,7,8). But for m+n should be a multply of 9, meaning that n also can be zero. Thus the value of
m+n will be 9.
for x+y to be a multiple of 9. Since
we are getting a unique value. We can eliminate options. B,C and E. Taking statement 2.
According to statement x*y= (9a+m)*(9b+n)=9c+5, On solving this
we get 81ab+9an+9bn-9c=5-mn on LHS and RHS respectively. We can see that
LHS is a multiple of 9. And
the absolute value of 5-mn has to be multiple of 9. Since we know that m>n. m cannot be zero. and 5-mn has to be mulptiple of 9 therefore n also cannot be 0. The only values satisfying the condition are
m=5 and n=1; m=7 and n=2. Since
we get two different value of m+n. We can eliminate option D.
The correct answer is option A.