Question

6. 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

Answer:

let us consider tens digit be x and units

digit be y.

So no. = 10x+y

Case l

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

40x+4y = 70y + 7x

33x - 66y = 0

x - 2y = 0 - (i)

Case ll

x - y = 4 -(ii)

Subtracting equation ii and i

x - 2y = 0

x - y = 4

- + -

-y = -4

y = 4

putting value of y=4 in equation I

x - 8 = 0

x = 8

then, no. will be 84

I hope it will help u

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.