Question

the sum of the digit of a two digit number is 10 .The number is decreased by 36 ,if the digit is reversed .Find the number

Answer 1

•x+y=10
10x+y-36=10y+x
•9x-9y=36

x=7
y=3

so 73 is ans

Answer 2

Let the two digit number be 10x + y

The sum of its digits i.e x + y = 10(equation 1)

If 36 is subtracted from the number then the digits are interchanging.
10x + y - 36 = 10y + x
9x - 9y = 36
Taking 9 as common
x - y = 4 (equation 2)

On adding equation 1 and 2
x + y = 10
x - y = 4
2x = 14
x = 7

x + y = 10
y = 10 - x = 10 - 7 = 3

The number is 10x + y = 10*7 + 3 = 73