Question

Seven times a two digit number is equal to
four times the number obtained by reversing
the digits. If the difference between the digits
is 3, find the number.​

Answer 1

Let the two digits of a two digit number be x and y.

The two digit number so formed will be 10x+y,where digit x is at 10's place and y is at 1's place( unit place).

By question, 7(10x+y) =4(10y+x)...............(1)

And,. (x-y)=3...….......................................(2)

From (2),. x=(y+3).................(3)

From(1),. 70x+7y =40y+4x

Or, 66x=33y

Or,2x=y....................(4)

Solving (3) and (4),

x =(2x+3)

Or,x = -3.

Putting this value of x, we get

y=2x =-6.

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 :

a b - b = 3

b = 3

= > a = 6

Hence number = > 30 + 6

= > 36.