Question

sum of a digit of a two digit number is 7 if the digits are reversed the number of formed is 9 less than the original number find the original number

Answer 1

let the unit digit=X
then ten digit= 7-x
the original no.is=10×(7-x )+(X)
so, original no.=70-10x+X =70-9x
According to question if the digit is reversed
then=10(X)+(7-x) =10x+7-x =9x+7
now the original no. is greater than the reverse no. by 9
so,9x+7+9=70-9x
9x+16=70-9x
9x+9x=70-16
18x=54
X=54÷18
x=3
original no.= 10(7-3)+(3). replacing x by 3
we get =70-30+3=43
so,the original no. is 43
I hope it will help u