Question

4. The sum of digits of a two digit number is 15. The number obtained by reversing
order of digits of the given number exceeds the given number by 9. Find the given
number.


​

Answer 1

$HEYA \: \\ \\ let \: the \: two \: digit \: number \: be \: xy \\ \\ according \: to \: the \: given \: question \: \\ \\ x + y = 15...equation \: (i) \\ \\ 10y + x = 10x + y + 9 \\ \\ 9x - 9y = 9 \\ \\ x - y = 1...equation \: (ii) \\ \\ add \: both \: the \: equations \: we \: have \: \\ \\ 2x = 16 \\ \\ x = 8 \: \: \: \: and \: \: \: y = 7 \\ \\ so \: the \: two \: digit \: number \: is \: \: \: \: \\ \\ 87$

Answer 2

10y+x

y+x= 15

x=15-y

10y+x+9=10x+y

now put the value of x here (x=15-y)

10+15-y+9=10 (15-y)+y

9y+24=150-9y

9y+9y=150-24

18y = 126

y = 126÷18

y= 7

THE NUMBER IS

X= 15-7

X= 8

ANSWER IS 87