Question

sum of the digit of a two digit number is 15 the number obtained by interchanging the digits exceeds the given number by 9 find the number

Answer 1

well listen,
Let x and y be the tens digit and units digit respectively
Now, ATQ,
x+y=15
or, we may write x=15-y .....(i)

Now let's move forward,
ATQ,
(10y+x)-(10x+y)=9
or, 10y+x-10x-y=9
or, 9y-9x=9
or, 9(y-x)=9
or, y-x=9/9=1
that is, y-x=1
Now substituting x we get,
y-x=1
or, y-(15-y)=1
or, y-15+y=1
or, 2y=1+15=16
or, y = 16/2=8

Now we know y=8
so, x = 15-y=15-8=7
so the no. is 10x+y=10*7+8=78

Answer: 78

Answer 2

Answer:

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