Question

7 times a 2 digit number is equal to 4 times the number obtained by interchanging digits and difference is 3, find the number

Answer 1

let no. = 10x+y
interchanged no. =10y+x
7(10x+y)=4(10y+x)
70x+7y=40y+4x
66x-33y=0
this is equal to 2x-y=0.......(1)
y-x=3........(2)
from (1) and (2)
x=3
put in x in (1)
y=6
no. 10x+y
=10(3)+6
=30+6
=36
so no. obtained is 36.