Question

Seven times a two digit number equals four times the number with digits reversed. Find the number if the sum of the digits is 3.

Answer 1

Let us assume, x and y are the two digits of the two-digit number

Therefore, the two-digit number = 10x + y and reversed number = 10y + x

Given:

7 (10x + y) = 4 (10y + x)
70x + 7y = 40y + 4x
66x - 33y = 0
6x - 3y = 0 -----------1

Also given:

x + y = 3 -----------2

Multiply equation 2 by 3

3x + 3y = 9 --------------3

Adding equation 1 and 3

9x = 9
x = 1

Therefore, y = 3 - x = 3 - 1 = 2

Therefore, the two-digit number = 10x + y = 10 * 1 + 2 = 12

Answer 2

Answer:

12

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' sum is 3 .

a + b = 3  ( ii )

From ( i ) and ( ii ) we get :

2 b + b = 3

b = 1

= > a = 2

Hence number = >  10 + 2

= > 12.