Question

Four times a certain two digit number is seven times the number obtained on interchanging its digits if the difference between the digits is 4
Find the number

Answer 1

4(10x + y) = 7 (10y + X)

simplify to get relation between X n y
then use relation x-y = 4
and use elimination method

Answer 2

Answer:

36

Step-by-step explanation:

Let the unit digit be a and tenth unit be b .

So , number = 10 b + a

It's said number is seven times is equal to reversing the order of its digit.

= > 7 ( 10 b + a ) = 4 ( 10 a + b )

= > 70 b + 7 a = 40 a + 4 b

= > 66 b = 33 a

= > a = 2 b ... ( i )

Also given numbers' difference is 3 .

a - b = 3  ( ii )

From ( i ) and ( ii ) we get :

2 b - b = 3

b = 3

= > a = 6

Hence number = > 30 + 6

= > 36.