Question

The sum of digits of a two digit number is 15.the number obtained by reversing the order of digits of the given number exceeds the given no. by 9. find the number.

Answer 1

let the unit digit be x and tens place to be y
number be 10y+x
x+y=15..... (1)
10x+y-10y-x=9
9x-9y=9
x-y=1... (2)
By subtract
x+y-x+y=15-1
2y=14
y=7
from equation 1
x+y=15
x+7=15
x=15-7=8
number =10y+x
10×7+8=78

Answer 2

Answer:

Step-by-step explanation:

Solution::

Let the digit be x and another digit be y

number be 10y+x

x+y=15..... (1)

Now

10x+y-10y-x=9

9x-9y=9

x-y=1... (2)

x+y-x+y=15-1

2y=14

y=7

from 1

x+y=15

x+7=15

x=15-7=8

number =10y+x

10×7+8

=78

Therefore the number is 78